128 BIT 32x4 PROMS?

Question

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

WangoTango · Accepted Answer

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 :

Peter Hill · Answer

Found the hardware ref manual in the attic, yup it's 32x8, 7603. Alsoseems to be 50ns not 20ns.Usual rate of exchange 1 GPB = 1 USD? Peter HillSpamtrap reply domain as per NNTP-Posting-Host in headerCan of worms - what every fisherman wants.Can of worms - what every PC owner gets!

whit3rd · Answer

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

WangoTango · Answer

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.

128 BIT 32x4 PROMS?

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