Date   : Wed, 09 Oct 2002 00:37:43 +0100 
From   : Andrew Hancock <Andrew.Hancock@...>
Subject: Re: Copying Paged eproms on a carrier

 
If it's the same Multiprom that I have, it can only handle 2764 -
27256.
The dip switches are used to page in, each 16k bank, upper and lower.

Therefore the eprom must be programmed in two separate actions, low
and then high. There was never enough memory in the beeb, to read the
entire
32k contents.

Andrew

-----Original Message-----
From: Sprow [mailto:info@...] 
Sent: 07 October 2002 00:05
To: bbc-micro@...
Subject: Re: [BBC-Micro] Copying Paged eproms on a carrier

In article <004101c26dc8$8cf74fa0$af4e893e@...>,
   Alastair Seggie <alastairseggie@...> wrote:
> Hi all
>
> About a year ago I bought an old Denford Starturn 8 CNC lathe this
> runs  off a BBC computer Via the 1MHz bus. It has an EPROM that has
> to be  inserted in to the BBC before it will work.

[snip]

> Now the problem I have is that the EPROM I am talking about is not
> mine.  

The 20 pin device is a PAL (or GAL) which hovers on a few address
lines and
outputs a couple of chip selects.
One scheme I considered was to have branch locations at known points
in the
ROM which were just
 .page0
 RTS
 .page1
 RTS
 .page2
 RTS
 .page3
 RTS
then to swap pages you push the desired routine address (-1) on the
stack
and JMP to page<whatever>.The PAL then swapped the ROM round the
processor
finds an RTS and everyone's happy.

Not sure if this is exactly how our lathe does it,but you might try
swapping
the ROM for an Interword carrier to see if it still works.

> I also need any information on the "Multiprom" EPROM Programmer 
> specifically will it copy large EPROM's so I could copy this one.
> Any Info  on the programmer would be appreciated.

If it's small,beige,plugs into the user port with 8 DIP switches
labelled A
and B then it can handle anything from 2764 (8k) to 27512 (64k),
Sprow.

> Alastair