Search found 21 matches

by zx-heinz
Sun Dec 06, 2020 6:50 pm
Forum: Hardware
Topic: ZX81 Joystick interface
Replies: 9
Views: 702

Re: ZX81 Joystick interface

Have a look here:
https://forum.tlienhard.com/phpBB3/view ... 739#p43739
It is designed for the ZX Spectrum, but it would be easy to adapt it to the ZX81. The advantage: It is programmable, so you can play even all games which are designed only for keyboard use.
by zx-heinz
Tue Nov 03, 2020 11:46 am
Forum: Software
Topic: Drop the PRINT instruction on ZX80
Replies: 8
Views: 920

Re: Drop the PRINT instruction on ZX80

The command makes sense, the result of the printing is only displayed when the boolean result from the USR call is true, which it is when BC >0. However the PRINT itself wil print nothing even when BC >0, the ; will keep the cursor on the same line and not to the next line. Your problem is differen...
by zx-heinz
Sun Nov 01, 2020 11:58 am
Forum: Software
Topic: Drop the PRINT instruction on ZX80
Replies: 8
Views: 920

Re: Drop the PRINT instruction on ZX80

LET A=USR 30000 or PRINT “” AND USR 30000; This doesn't solve my problem really. First point is that ( "" AND USR 30000) is not an admissible expression. The first term is a string, the second a number, and AND is expecting numbers. But I want to go more in the details: The command under discussion...
by zx-heinz
Sat Oct 31, 2020 6:28 pm
Forum: Software
Topic: Drop the PRINT instruction on ZX80
Replies: 8
Views: 920

Drop the PRINT instruction on ZX80

I have a question concerning MC on ZX80. Suppose, I have poked a RET ($C9) at address 30000. The command PRINT USR(30000) will come back with 30000. But I want to surpress the printing. How can I drop the PRINT instruction from the stack?
Is there good textbook for MC programming on ZX80?
by zx-heinz
Sat Aug 29, 2020 11:07 am
Forum: Hardware
Topic: This weekends projects
Replies: 53
Views: 23706

Re: This weekends projects

Hello Matthew, nice project. Do you have a spare PCB for me? It would be interesting to compare your board with our recent construction (rune and me) which can be found in https://forum.tlienhard.com/phpBB3/viewtopic.php?p=45188#p45188 The address decoding is much poorer than yours, but the filterin...
by zx-heinz
Mon Aug 10, 2020 5:02 pm
Forum: Hardware
Topic: This weekends projects
Replies: 53
Views: 23706

Re: This weekends projects

Interesting project. What about the software? Will it be as powerful as the CurrahµSpeech software?
by zx-heinz
Mon Aug 10, 2020 4:59 pm
Forum: Hardware
Topic: "mic" and "ear" labels are confusing
Replies: 3
Views: 2552

Re: "mic" and "ear" labels are confusing

As already mentioned by MAK1024 the signal level at the MIC connector is much much smaller than a "line out level" of temporary voice recorders. It is just 5mV in contrast to 200mV for the last mentioned. Make sure you have the right equipment for that.
by zx-heinz
Fri Jul 03, 2020 11:24 am
Forum: Hardware
Topic: Memotech 16K Ram pack failure
Replies: 14
Views: 1909

Re: Memotech 16K Ram pack failure

gseb wrote: Thu Jul 02, 2020 12:15 am My PSU is a modern 9V one, it output just 9V. This is working fine with a sinclair 16ko Pack though the sinclair one may generate the 12V differently....
Could you try with an original PSU? Cause of 9V<10.8V, the instructed minimum for 4116.
by zx-heinz
Wed Jul 01, 2020 9:22 am
Forum: Hardware
Topic: Memotech 16K Ram pack failure
Replies: 14
Views: 1909

Re: Memotech 16K Ram pack failure

Hi,
it is more reliably to check the -5V at pin1 of the RAMs. Some Memotech RAM don't generate the 12V but use instead of the 9V from the power supply. If the -5V is missing, you have to repair something. First check.
by zx-heinz
Fri Jun 26, 2020 10:25 am
Forum: Hardware
Topic: ZX80 Video Ouput - Diagonal Lines
Replies: 6
Views: 1029

Re: ZX80 Video Ouput - Diagonal Lines

SHZ88 wrote: Thu Jun 25, 2020 9:18 pm The image does appear to change, whenever I press on the PCB or "fiddle" with the power input.
Check the voltage during "fiddeling" with your meter. Is it stable? Sometimes the power connector has dry or broken joint. Use a magnifier glass.
Heinz