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!

In article , peter.usenet1
@nospam.demon.co.uk says...
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

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 :

http://www.datasheetcatalog.org/data...ips/82S123.pdf

On Sat, 8 Aug 2009 11:31:39 -0400, WangoTango
wrote:

In article , peter.usenet1
says...
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

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 :

http://www.datasheetcatalog.org/data...ips/82S123.pdf

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?
http://www.cricklewoodelectronics.co...&pa ge=5&js=n
--
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!

On Aug 8, 6:33*am, Peter Hill
wrote:
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.
....
decode the 5 input lines and select the memory bank in 20ns

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.

In article , peter.usenet1
@nospam.demon.co.uk says...
On Sat, 8 Aug 2009 11:31:39 -0400, WangoTango
wrote:

In article , peter.usenet1
says...
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

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 :

http://www.datasheetcatalog.org/data...ips/82S123.pdf

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?
http://www.cricklewoodelectronics.co...&pa ge=5&js=n

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.