MANUAL - hunter memory board

[David G]

also see: General information about the hunter memory board

The instruction/usage/assembly manual for the HUNTER 8K NONVOLATILE MEMORY board is enlightening. The board features

• SRAM (static RAM), EPROMs or a mix of SRAM+EPROM

• optional battery backup keeps your programs for months

• reset button

• configuration jumpers

• passthrough edge connector

Apparently, there were different revisions of the board. This manual is "ISSUE 5"
* Issue 5 manual scans
* Issue 5 manual on archive.org

CONTENTS
1 Introduction
1 Configurable memory blocks
2 Memory Block 0 (System ROM) & Block 1 (system-transparent RAM)
3 System/User RAM (Block 2 & Block 3)
3 Assembly - Equipment
4 Assembly - Components
5-7 Assembly - Procedure
7 Memory check [BASIC type-in]
8 Memory check [ASM type-in]
8 Battery back-up
8-9 What to do if it doesn't work [troubleshooting]
9 Other Options - To use with a ZX80
9-10 Other Options - Modifications for 2716 EPROM's
10 Other Options - Modifications for a RAM/EPROM mixture
10 Other Options - Modifications for EPROM's
11 Modificatsions for use as system RAM
11-12 Using the board in a system with more than 32K
12 Write Protect switch
13 Paging
13 Parts list
14 Schematic diagram
15 [Type-in] A sample display routine
17 [Type-in] Screen dump
17 [Type-in] Reload display file
17 [Type-in] Fill dumped display file with character N
17 [Type-in] Save your machine language routines on tape
18 [Type-in ASM] Generate REM statment
18 [Type-in ASM] Dump or load transparent memory
19-20 Merging BASIC programs
19 [Type-in ASM] Dump to transparent memory
19 [Type-in ASM] Generate space and reload program
20 [Type-in] Renumbering lines
20 [Type-in ASM] Amount of free space in memory

[David G]

This documentation is "Issue 5 March 1984" ( index )

the board can use any 8K block in the first 32K of memory in the address space. The four blocks are:

• BLOCK 0 (0-8K) normally used by system ROM

• BLOCK 1 (8-16K) normally unused. Transparent to the ZX81 system

• BLOCK 2 (16-24K)[ available RAM

• BLOCK 3 (24-32K) available RAM

page 1

PH
8K NONVOLATILE MEMORY
FOR ZX80, ZX8l, TS1000, AND TS1500 MICROCOMPUTERS
=================================================

INTRODUCTION

The memory board you have received can fill any one of the four 8K blocks of memory in a 32K system. These blocks of memory are illustrated in Figure 1 with their appropriate addresses. If your system is larger than 32K refer to the modification outlined on page 11 of this manual.
FIGURE 1

Code: Select all

   |   8K    |      8K       |     8K      |      8K
   | 0 to 8K |    8 to 16K   |  16 to 24K  |   24 to 32K
   |----------------------------------------------------
   | system  |transparent to |  - -  available RAM   - -
   |   ROM   |SINCLAIR system|
   |----------------------------------------------------
   | BLOCK 0 |    BLOCK 1    |   BLOCK 2   |   BLOCK 3
A13|   0     |      1        |     0       |     1
A14|   0     |      0        |     1       |     1

The first 8K is occupied by the operating system and BASIC interpreter of the ZX81 computer. You can modify the SINCLAIR system by using this board in the 0 to 8K slot.

The second 8K is not occupied and is an ideal place to store your own system utilities and machine language routines. It is primarily for this location that this 8K board, with its nonvolatile memory, is designed.

The remaining 16K is available for Sinclair BASIC system RAM. It may be 1K for a simple ZX81, 2K for an upgraded ZX81 or TS1000, or 16K for a system with a 16K RAM pack. Note that if you require a full 16K of system RAM it is more economical to purchase a Sinclair RAM pack rather than use two of these boards. However, this board can be jumper-programmed to occupy either 8K of system RAM.

Selection of the different 8K blocks of memory is achieved by jumper Jl as shown in Figure 2.
FIGURE 2

Code: Select all

          |-----|-- jumper position when used as
          |     |   system-transparent RAM 8-16Κ
      -------------
  Jl  | ο ο ο ο o |

      -------------
Block   0 1 2 3 Common

Each configuration will be described in turn.

==================================
Copyright (1982): Paul Hunter, 1630 Forest Hills Dr., Okemos, Michigan 48864 and Gernsbach Publications, Inc., 200 Park Avenue South, New York, NY 10003
Issue 5 March 1984

[David G]

This documentation is "Issue 5 March 1984" ( index )

• BLOCK 0 (0-8K) SYSTEM ROM

• BLOCK 1 (8-16K) SYSTEM TRANSPARENT RAM

PH
Page 2 8K NONVOLATILE MEMORY
============================
SYSTEM ROM 0 - 8K

This configuration is used only when you wish to modify the Sinclair Operating system. The board can be populated by HM6116LP CMOS RAM with low-power back-up or by 2716 or 2732 EPROM's. Jumper configurations for the different memory devices are discussed in the next section. Note that the character table in ROM is addressed by the Sinclair system logic chip and not by the CPU (the address bus is split). Initially you may wish to retain access to the character table (7680 to 8191 or 7.5K to 8K). Note that the character table is read during the refresh cycle and that access to the ROM should be allowed when _RFSH_ is low (active).

SYSTEM TRANSPARENT RAM 8 - 16K

The block of memory from 8 to 16K is transparent to the Sinclair system -- it doesn't know it's there. This area of memory is therefore an ideal place to store, either permanently or temporarily, machine language routines or data which are to be used by the BASIC system. Some examples of routines you might store in this block of memory are:

* fast graphics routines
* custom mathematical or statistical functions
* Sinclair code / ASCII conversion tables
* octal/decimal/hex conversion routines
* I/O servicing routines for control applications
* a checksum routine
* a routine for resequencing BASIC programs
* a routine for merging BASIC programs and other toolkit utilities
* a disc operating system (DOS) or other development system
* speech synthesis routines
* additional BASIC commands
* EPROM programming routines

Sample routines are described at the end of this manual.

The use of HM6116LP-3 2K CMOS RAM memory IC's with a back-up power supply means that routines stored in the RAM are nonvolatile -- the RAM retains its memory even when the ZX81 is switched off or reset. Moreover, being RAM, the routines stored in the memory are easily modified. The lithium cell supplied with the board should maintain sufficient reserve power for about ten years for a fully populated board. See note on page 8.

Once you have established your system utilities and other machine language routines, you may wish to replace the 6116LP-3 CMOS RAM's by 2716 or 2732 EPROM's or equivalent EEPROM's. This board can accomodate EPROM's in place of the CMOS RAM's. Jumper J2 is used to select the memory device type as shown in Figure 3. A mixture of RAM and EPROM is allowed -- see page 10.

Note that some commercially available accessories for the ZX81 system -- such as printers or disc drives -- allocate same portion of the transparent 8K block to the control of these systems. To accomodate such peripherals, the board can be partially populated. Alternatively, a paging system may be used. In such a system several devices occupy the same region but only as is enabled or selected at a particular time -- see page 13.

[David G]

hunter manual Page 3 SYSTEM/USER RAM and ASSEMBLY EQUIPMENT
This documentation is "Issue 5 March 1984" ( index )

Page 3 8K NONVOLATILE MEMORY
============================

Figure 3

Code: Select all

--------  --------  --------
| o  o |  | o  o |  | o--o |
| |    |  | |  | |  |      |
| o  o |  | o  o |  | o--o |
|    | |  |      |  |      |
|    o |  |    o |  |    o |
|JU2   |  |JU2   |  |JU2   |
--------  --------  --------
  FOR       FOR       FOR
HM6116P-3   2716      2732

SYSTEM AND USER RAM 16 - 32K

The board can be configured to occupy either 8K blocks of memory in the 16 of system/user RAM. You have, in addition, the option of disabling the internal 1 or 2K RAM of the ZX81 or Timex 1000, or of keeping the 2K of an upgraded system enabled and only partially populating the 8K board. Jumper J3 is used for this (see Figure 4).

The battery backup-up and associated circuitry is not required if the board is to used solely as system/user RAM. See page 11.

FIGURE 4

Code: Select all

          |---|
          | o |
Jumper J3 | | |   insert diode D4 here if
          | I |== internal 2K RAM is to
          | v |   be used
          | - |   (leave Socket 0 empty)
          | | |
  --------  | |
  | o-------o |
  |-----------|
        ||  
or place a wire jumper here to
disable the internal 1 or 2K RAM

A jumper is inserted in J3 ONLY when the board is configured a system RAM in the region 16K to 24K. Note that Figure 12 on page 84 of the Radio-Electronics article is incorrect.

ASSEMBLY
--------
PLEASE READ THE INSTRUCTIONS CAREFULLY BEFORE STARTING TO ASSEMBLE YOUR BOARD.

EQUIPMENT NEEDED

A small electric soldering iron (15 to 25 watt) with a fine or micro tip
Fine gauge multicore solder (rosin core; 60/40 tin/lead)
A pair of diagonal wire cutters or some other means of cutting component leads
A multimeter, simple logic probe, or circuit-continuity tester

The board will probably take from two to four hours to assemble -- choose a well-lit workspace where you can organize the components and assemble the board undisturbed.

[David G]

This documentation is "Issue 5 March 1984" ( index )

Page 4 8K NONVOLATILE MEMORY

COMPONENTS

DO NOT REMOVE THE CMOS RAM IC FROM ITS PROTECTIVE FOAM UNTIL NECESSARY.

Check and identify each component against the parts list. Note the polarity of the diodes, the tantalum capacitor, the transistors, and the IC's as shown in Figure 5. The polarity of the lithium cell is marked on it.

FIGURE 5

diode NPN transistor tantalum capacitor IC (from top)

The printed circuit board is silkscreened with the parts placement diagram shown in Figure 6. All components except two are mounted on the side with the printing and all the soldering is done on the other side marked "citcuit side".

The following procedure assumes that the board will be allocated the transparent region 8 - 16K and that 6L16LP-3 CMOS RAM's with a back-up power supply will be used. Changes to the procedure for other options are summarized later -- refer to these now if you choose an alternative option. The use of movable jumpers allows you to keep your options open and vary the use to which you put the board.

FIGURE 6 COMPONENT SIDE

FIGURE 7
at least 0.25 inch

Epoxy pc connector edgeways to bottom of pc board. Use AP headers to connect traces
Mother board

[David G]

This documentation is "Issue 5 March 1984" ( index )

Nice instructions, including a check-circle to check off as you proceed to assemble the board

Page 5 8K NONVOLATILE MEMORY

PROCEDURE

O
Refer to Figure 6. Solder in place the four 24 pin IC sockets. Make sure your soldering iron is clean and hot and use a minimum amount of solder. The bond should be shiny in appearance -- not a dull grey. Cold solder joints and solder bridges between traces are the most probable causes of ultimate malfunction. Always double check that the component is in the correct place before soldering. It's sometimes very difficult to remove a component from a pc board without damage either to the board or to the component.

O
Solder the 16 pin IC socket in place --- note the polarity.

O
Refer to Figure 7. Note that there are three ways to attach the memory board to your ZX8l. If you have an expansion or mother board with the same signal arrangement you might prefer to use AP headers as shown in Figure 7b or c. Otherwise use the method shown in Figure 7a as follows. Insert the edge connector in the appropriate holes in the board. Adjust the stand-off from the board to at least 0.25". Make sure the connector is parallel to the board and solder one pin at each end. Check the alignment again and if you're satisfied solder the remaining pins on the connector.

O
On the circuit side of the board, bend the wrap post pins at each end of the socket in toward each other as shown in Figure 7. Secure the edge connector board between the two pairs and check the alignment. Solder these four pins. Now bend the remaining pins down onto the connector. Make sure that each pin is in contact with the appropriate trace on the connector. Solder the pins. (Make sure that the polarizing key is in the correct slot.)

O
Solder in place the 100 ohm resistor R1 (brown-black-brown). See note below about omitting Ε1 (Fifth instruction on next page).

O
Solder in place the four 1K resistors R2-R5 (brown-black-red).

O
Solder in place the six 10K resistors R6-R10 & R12 (brown-black-orange).

O
Solder in place the 100K resistor R11 (brown-black-yellow).

O
Solder in place the three diodes D1 - D3. Note the polarity -- the black band toward the top of the board. Note that D3, the germanium diode, is larger than the silicon diodes.

O
Solder in place the four ceramic capacitors C2 - C5. These can go in either way round. Note that C3 can be omitted ~- see note on the write-protect switch.

O
Solder the tantalum capacitor C1 as close to the board as possible -- the positive lead must go in the hole nearer the bottom of the board. (For a ΖX80 computer, mount C1 on the circuit side.)

O
Solder the five NPN silicon transistors in their appropriate places. Note that the curved side of all transistors face the left. The transistor leads must be gently spread apart before mounting them in the appropriate holes. Be careful not to overheat the transistors when soldering them -- let the transistor cool before going on to the next lead. Mount Q1 as close to the board as possible.

[David G]

This documentation is "Issue 5 March 1984" ( index )

Page 6 8K NONVOLATILE MEMORY

O
Solder jumper J1 in the appropriate holes (see Figure 2). If you intend to vary the 8K memory block to which the board is assigned then you may wish to use sockets for the jumper. Leads cut from the diodes or resistors may be used as jumper wires.

O
Jumper J2 is configured as shown in Figure 3 for 6116LP-3 CMOS RAM. Insert the two jumper wires and solder in place.

O
Jumper J3 should not be inserted.

O
Jumper J4 is a diode D4. Note the polarity (black band to the right). Insert and solder in place.

O
Add the reset switch on the back of the board where there is more room for your finger. You may of course omit the switch and its associated resistor R1. It is recommended, however, that you use the switch to reset the CPU instead of pulling the power plug -- if the power is removed and then quickly restored the filter capacitor in the power supply, and the reset capacitor in the ZX81, may not fully discharge. This means that the Z80 CPU may accidentally write over your nonvolatile memory when it comes alive.

O
Jumpers J5 and J6 are not used and should be left vacant.

O
Solder the lithium cell holder on the reverse side of the board. Press the holder firmly against the board while soldering in place.

O
At this stage the board should be thoroughly checked. Look at all the solder joints and recheck the placement of components. Refer to Figure 8 and connect +5V and ground to the appropriate pins of the edge connector. Check for the presence of +5 and ground at each IC socket. Pinouts of the IC's are illustrated in Figure 9.
Disconnect the supply.

O
Plug IC5 into its socket. If the pins are spread too wide bend them in very gently by pressing an entire row of pins on one side of the IC against a hard surface. A piece of aluminum foil on wood works well and provides a grounded surface.

O
CMOS devices are in general susceptible to damage by static electricity. Before taking the CMOS memory out of its protective foam ground yourself to remove any static charge. If you need to rest it somewhere place it on a piece of aluminum foil. Never place the device on a non conducting surface. You will probably have to bend the pins inward in order to fit the IC in its socket. Do so by gently pressing a row at a time on a grounded surface as described above. Plug the memory into the first socket (Socket 0).

O
Do not add the lithium cell yet.

Code: Select all

FIGURE 8

     1B|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|23B
UNDER  |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
 SIDE  |   |   |   |---|  _|_  |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  _|_
       5V  9V SLOT  0V     0   A0  A1  A2  A3  A15 A14 A13 A12 A11 A10 A9  A8  A7  A6  A5  A4 ROM
                                                                                              C.S.

     1A|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|23A
  TOP  |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
       |  _|_  |   |   |   |   |   |   |   |   |  _|_ _|_  | __|_ _|_ _|_  | __|_  | __|__ | __|__
      D7' RAM SLOT D0' D1' D2' D6' D5' D3' D4'INT NAY HALT | 1ORQ  RD  WR  | WAIT  | RESET | REFSH
          C.S.                                            _|__           __|__   __|__    _|_
                                                          MREQ           BUSAK   BUSRQ     M1

[David G]

hunter manual Page 7 ASSEMBLY PROCEDURE (cont.) and MEMORY CHECK [Type-in]
This documentation is "Issue 5 March 1984" ( index )

Page 7 8K NONVOLATILE MEMORY

FIGURE 9

HM6116LP-3 74LS139


MEMORY CHECK

ALWAYS SWITCH OFF YOUR ZX81 BEFORE ADDING OR REMOVING THE 8K BOARD.

Its just as well to check the memory board with only one 2K CMOS RAM IC plugged in. If it works with one then the board can be fully populated and tested again.

Switch off the power and plug the board into the back of your ZX81. Do not add any other peripherals at this stage (one thing at a time). Switch on.

If the CMOS RAM board is to be used in the 8K slot from 16 to 24K then the Sinclair software can be used to test the memory. The top of system RAM is a variable 'RAMTOP' stored in memory locations 16388 and 16389 (decimal). The command PRINT (PEEK 16388 + 256*PEEK 16389)/1024-16;"K" will print the size of system RAM. Note that not all of this memory is available to the user. Some of it is used for system variables (like 'RAMTOP'), some for the display file, some for the Z80 stack, etc.

If the CMOS RAM board is used in the 8 to 16K slot, then a simple test to check whether the board is functioning properly is to POKE 9000,N and then PRINT PEEK 9000 and see if you get the same N back again. (N is any decimal number between 0 and 255.) The address 9000 can be any number between 8192 and 10239 if the CMOS RAM chip is in Socket 0 The following BASIC program will test every address in the 2K of transparent RAM. It takes a long time (even in FAST mode -- the SLOW mode takes 4.5 minutes) and the machine language routine on the next page completes the test in a fraction of the time. This machine language routine is placed in a REM statement in system RAM --- intentionally or it would self-destruct.

BASIC PROGRAM TO CHECK EVERY MEMORY LOCATION BETWEEN 8192 AND 10239

Code: Select all

   5 FAST
  10 FOR N = 8192 TO 10239 
  20 POKE N, 1
  30 NEXT N  
  40 LET A = 0
  50 FOR N = 8192 TO 10239
  60 IF PEEK N-1=0 THEN LET A=A+1
  70 NEXT N
  80 PRINT "CMOS MEMORY = ";A/1024;"K"

[David G]

This documentation is "Issue 5 March 1984" ( index )

Page 8 8K NONVOLATILE MEMORY
============================

MACHINE LANGUAGE PROGRAM TO CHECK EVERY MEMORY LOCATION BETWEEN 8K and 16K

First enter the BASIC program:

Code: Select all

  10 REM 123456789012345678901
  20 PRINT "TRANSPARENT CMOS MEMORY";USR 16514 1024;"K"
  30 STOP

Now POKE in the following machine language program. You can poke the data into each location individually or you can use a short program like that on page 15.

Code: Select all

Address   Data       Assembly language (Mnemonic)
16514     33 255 63  LD HL. (top of memory)
           1   0  0  LD BC. 00
16520     62  31     LD A, 31
          54  01     LD (HL), 01
          43         DEC HL
         188         CP H
          32         JNZ
         250         back 5 lines
          35         INC HL
           3         INC BC
16530     53         DEC (HL)
          40         JZ
         251         back 4 lines
          11         DEC BC
16534    201         RET

If you list the BASIC program now you will see that the REM statement contains characters corresponding to the data POKEd in. Now enter RUN.


BATTERY BACK-UP

At this point, if all is well, the lithium cell can be placed in its holder -- slip it gently under the positive terminal. POSITIVE SIDE UP.

When the 8K nonvolatile memory board is not in use, leave it plugged into the ZX81 -- even when the ZX81 is not switched on. Doing this effectively keeps the address and data lines to the CMOS RAM chips from floating high and ensures that the drain on the lithium cell stays below 1 microamp for a fully populated board -- an insignificant current.

An equally good technique is to plug a scrap piece of double-sided pc board into the 44-pin connector when the board is disconnected from the computer. (Short both sides of the double-sided pc board together.)


WHAT TO DO IF IT DOESN'T WORK

Remove the CMOS IC and leave in a safe place -- on aluminum foil or back in its foam. Remove IC5.

Visually check the entire board --- look for poor solder joints and solder bridges. They are the most likely causes of malfunction. The most probable place for a faulty solder joint is on the edge connector.

Make sure all components are placed correctly.

[David G]

This documentation is "Issue 5 March 1984" ( index )

Page 9 8K NONVOLATILE MEMORY
============================

Make sure the jumpers are correctly placed.

Without the IC's plugged in, connect the board to the ZX81 again and switch on. If you do not get a cursor then there must be either a solder bridge or an intermittent contact (again probably on the edge connector). If you obtain a cursor, power down, remove the board, plug in the IC's, and try again.

Clean the edge connector in your computer with a pencil eraser. Replace the IC's in their sockets and plug the board back in securely. Retest.

If the board still does not work remove the IC's again and check the continuity of all lines from edge connector to sockets and between sockets.

If the board works alone but not with a 16K RAM pack then look for a poor solder joint between the edge connector pins and the edge connector board. Sometimes solder flux on the edge connector inhibits contact -- make sure it is clean.

All parts supplied with this kit are guaranteed. Any part found to be defective will be replaced free of charge. Any part accidentally damaged by you will be replaced at cost. (List upon request.)

With some RAM packs, notably the Sinclair 16K RAM pack, you may experience a "wobble" problem. This lack of stability in the RAM pack causes intermittent contact in the signal lines between the 8K nonvolatile memory board and the RAM pack and will often lead to a system crash. A solution is to extend a rigid base backward from the computer. Double-sided adhesive foam can be used to fix the various components of the system to this base.

Occasionally, with about 2% of all ZXB81/TS1000's, you may see the characters on the screen appear to disintegrate into "chinese characters" after the machine has been on 5 or 10 seconds. This problem will often disappear if the board is fully populated or if a RAM pack is added on behind. In any event, the cure is straightforward and if you experience this problem let me know immediately.


OTHER OPTIONS
-------------

TO USE WITH A ZX80

A ZX80 computer does not have _ROMCS'_ available at the edge connector. It is necessary to make it available at 23B if the board is to be used for the transparent 8K block. Break the trace from the decoder IC6 pin 7 to the ROM pin 20 in the ZX80, bridge the break with a 680 ohm resistor, and wire a jumper from the _CS_ pin 20 on the ROM to pin 23B on the edge connector.


MODIFICATIONS FOR 2716 EPROM'S

If the board is to be fully populated by 2716 EPROM'S, resistors R2 to R12, all transistors Q1 to Q5, diodes D1 through D3, and the lithium cell should be omitted. Diode D3 should be replaced by a wire jumper and wire jumpers should also be inserted to connect the collector socket of each transistor Q2 through Q5 to the corresponding emitter socket. Jumpers J2 should be placed as shown in Figure 3. Jumper J1 should remain in position 1 for the 8 - 16K assignment and diode D4 should remain inserted in jumper J4.