Search found 452 matches
- Thu Sep 16, 2021 11:14 pm
- Forum: Hardware
- Topic: 32k Internal ram with m/c above 32k
- Replies: 14
- Views: 5471
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
- Thu Aug 26, 2021 10:45 pm
- Forum: Hardware
- Topic: 32k Internal ram with m/c above 32k
- Replies: 14
- Views: 5471
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..???
- Wed May 05, 2021 4:12 pm
- Forum: Hardware
- Topic: ULA revision
- Replies: 6
- Views: 2755
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...
- Sat Feb 13, 2021 1:28 am
- Forum: Hardware
- Topic: Spectrum 48K Upper Ram Fault
- Replies: 22
- Views: 9346
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 ..
- Sat Mar 10, 2018 4:23 pm
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 134455
Re: ZX81 ULA-in-a-CPLD
whoah!!!!
- Sat Feb 03, 2018 3:50 pm
- Forum: Hardware
- Topic: UK700 PSU running at 18.1 volts
- Replies: 14
- Views: 7348
Re: UK700 PSU running at 18.1 volts
or double up on the bridge diodes, use 2 in series for each quarter?...
- Sat Feb 03, 2018 3:49 pm
- Forum: Hardware
- Topic: UK700 PSU running at 18.1 volts
- Replies: 14
- Views: 7348
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...
- Sat Feb 03, 2018 3:40 pm
- Forum: Hardware
- Topic: zx spectrum in zx81 case
- Replies: 63
- Views: 44271
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...
- Mon Oct 23, 2017 7:26 pm
- Forum: Hardware
- Topic: UK700 PSU running at 18.1 volts
- Replies: 14
- Views: 7348
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???
- Mon Oct 23, 2017 7:24 pm
- Forum: Hardware
- Topic: UK700 PSU running at 18.1 volts
- Replies: 14
- Views: 7348
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...