Search found 452 matches

by gozzo
Thu Sep 16, 2021 11:14 pm
Forum: Hardware
Topic: 32k Internal ram with m/c above 32k
Replies: 14
Views: 4799

Re: 32k Internal ram with m/c above 32k

if you fit the m1not circuit, you dont need to 'deactivate' it if you have basic over 32768, it 'should' make no difference
by gozzo
Thu Aug 26, 2021 10:45 pm
Forum: Hardware
Topic: 32k Internal ram with m/c above 32k
Replies: 14
Views: 4799

Re: 32k Internal ram with m/c above 32k

its possible the mod the zx81 to allow machine code in the 32768 to 49151 area using the M1NOT mod, should be info on the 'net, maybe somewhere here ....i dont think its possible in any cases to run machine code above 49152 as thats where the dfile execution echo is and needs to be..???
by gozzo
Wed May 05, 2021 4:12 pm
Forum: Hardware
Topic: ULA revision
Replies: 6
Views: 2521

Re: ULA revision

dont think so, theres ways of telling what rom you have or if you have the rom fix board, but not ula, as far as i know, generally issue 1 boards will have 2c158 or 2c184 ulas, issue 3s 2c210 , but not necessarily always! you can tell board issue by looking in the expansion slot, if theres a transis...
by gozzo
Sat Feb 13, 2021 1:28 am
Forum: Hardware
Topic: Spectrum 48K Upper Ram Fault
Replies: 22
Views: 8783

Re: Spectrum 48K Upper Ram Fault

easiest replacement for the upper rams is a 4164 or equivalent, noting that it 'may' have to be a 128 cyle refresh type, not 256 as some are.? dunno if 256 cycles types work ok or not?? anyone??? may depend on the ram type link settings ..
by gozzo
Sat Mar 10, 2018 4:23 pm
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 238
Views: 123167

Re: ZX81 ULA-in-a-CPLD

whoah!!!!๐Ÿ˜Š๐Ÿ˜Š๐Ÿ˜Š๐Ÿ˜Š๐Ÿ˜Š๐Ÿ˜Š๐Ÿ˜Š
by gozzo
Sat Feb 03, 2018 3:50 pm
Forum: Hardware
Topic: UK700 PSU running at 18.1 volts
Replies: 14
Views: 6841

Re: UK700 PSU running at 18.1 volts

or double up on the bridge diodes, use 2 in series for each quarter?...
by gozzo
Sat Feb 03, 2018 3:49 pm
Forum: Hardware
Topic: UK700 PSU running at 18.1 volts
Replies: 14
Views: 6841

Re: UK700 PSU running at 18.1 volts

you could fit a couple of 1n5401s between the output of the bridge rectifier arrangement and the cap..? that'd drop the output a bit...
by gozzo
Sat Feb 03, 2018 3:40 pm
Forum: Hardware
Topic: zx spectrum in zx81 case
Replies: 63
Views: 39281

Re: zx spectrum in zx81 case

can anyone supply preprogrammed cplds for this zxmax, as i have bought an empty board, can find the other parts easily,.. i do have 3 'used' cplds but as to whether they can be erased and reused i dont know, plus i dont know what software or programmer device would be needed to program them...
by gozzo
Mon Oct 23, 2017 7:26 pm
Forum: Hardware
Topic: UK700 PSU running at 18.1 volts
Replies: 14
Views: 6841

Re: UK700 PSU running at 18.1 volts

and ..what mains voltage is it rated for and what is it running on. if its designed for 220v (but that would normally be a EU700? or something like that?) and being run on 240v , it will be high....maybe has a 220v transformer fitted in a uk/240v case???
by gozzo
Mon Oct 23, 2017 7:24 pm
Forum: Hardware
Topic: UK700 PSU running at 18.1 volts
Replies: 14
Views: 6841

Re: UK700 PSU running at 18.1 volts

hmm, may have shorted turns on the primary winding, does it get warm/hot after a while when on no load? if so it could have. also test voltage with a reasonable load...