1. Home
  2. Electronics Repair
  3. 128 BIT 32x4 PROMS?

128 BIT 32x4 PROMS?

Proms are Harris semiconductor but I've lost the orignal chip.

I've got a Zilog MCZ 1/05 development system. A memory decode prom on the 12/48K memory card (fitted with max 3x16K banks other 16k for 64k is on CPU card) has blown and was running hot.

About 10 years ago I made a decoder from TTL but it's 5 chips on a board attached to the socket by a flying lead. I've tried to reconfigure the memory so it bank switches the monitor EPROM for memory on the CPU card thus reducing the decode to a simple A14 and A15 bank select on the 48k card but hit a race problem.

I'd like something that can mounted on the socket instead of a card. Any ideas on lower chip count replacement? Even PIC or amtel if it can decode the 5 input lines and select the memory bank in 20ns

--
Peter Hill
Spamtrap reply domain as per NNTP-Posting-Host in header
Can of worms - what every fisherman wants.
Can of worms - what every PC owner gets!
Reply to
Peter Hill
Loading thread data ...

Are you sure it wasn't a 32 X 8 ? I have/remember 256 X 4 and 1024 X 4, but I haven't seen any 32 X 4. I have both the open collector and the tristate versions of the 32 X 8 BPROMs and I can program them too.

Here is a pinout of the 32 X 8 :

formatting link

Reply to
WangoTango

Found the hardware ref manual in the attic, yup it's 32x8, 7603. Also seems to be 50ns not 20ns.

Usual rate of exchange 1 GPB = 1 USD?

formatting link 

--
Peter Hill
Spamtrap reply domain as per NNTP-Posting-Host in header
Can of worms - what every fisherman wants.
Can of worms - what every PC owner gets!
Reply to
Peter Hill

...

Is this to decode 5 input lines into only 3 bank selects? Would a 74F138 do it? It takes three inputs plus three select lines, outputs 8 bank select signals - you might be able to OR outputs, there's some time slack.

With several 74F138's, you can do almost any 5-input decoder.

Reply to
whit3rd

formatting link

Do you have the hex/bin file or a truth table? I would be more than happy to program one up for you and toss it in the mail. Hell, with just 32 entries I could enter the bytes by hand faster than running the truth table through CUPL.

Reply to
WangoTango

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.