Tape read/write on expansion port?
Re: Tape read/write on expansion port?
Back on topic. Would this schematic have cassette output?
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Re: Tape read/write on expansion port?
The logic looks almost right. However, I think you may need the output from the other NOR gate (that forms the S-R flip-flop).
Are you intending to make this using standard logic chips (74xxzzz logic chips) or programmable logic?
Mark
Are you intending to make this using standard logic chips (74xxzzz logic chips) or programmable logic?
Mark
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ZX81 Chip Pin-outs
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Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
Re: Tape read/write on expansion port?
That would be 7400-chips. It's a proof og concept to connect to other hardware. Let's see what time will bring.
Re: Tape read/write on expansion port?
its looking a bit overly complicated.... you can do it with 2 dip 14 74xx chips, a 7400 nand gates and a 7432 or gate. look at the vsync latch on the zx80 shematic ... dont forget you dont really need all the address decoding... not any address decoding at all on the io write detect
Regards Andy
Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
- 1024MAK
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Re: Tape read/write on expansion port?
If you do intend to use 74 series logic, and want more than minimal address decoding, these chips are useful in reducing chip count:
- 74xx30 NAND Gate, 8 Input
- 74xx688 Digital Comparator
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
Re: Tape read/write on expansion port?
Nope. Can't remember where I hit a wall.
Re: Tape read/write on expansion port?
Hi Martin,
I redraw your logic drawing with dedicated LS ships :
Yes, something's wrong for the latch disable on /RD…
May be you had to use the /IOrq*Address bus=0 to release it…
Kicad schem files:
I redraw your logic drawing with dedicated LS ships :
Yes, something's wrong for the latch disable on /RD…
May be you had to use the /IOrq*Address bus=0 to release it…
Kicad schem files:
Xavier ...on the Facebook groupe : "Zx81 France"(fr)
Re: Tape read/write on expansion port?
I'm not going further with this. I have other projects.