BBC B+ 64k EEPROMs and SW RAM

for bbc micro/electron hardware, peripherals & programming issues (NOT emulators!)
Post Reply
User avatar
rmbrowngr
Posts: 315
Joined: Sat Jan 13, 2018 12:46 pm
Location: Dionysos, Greece
Contact:

BBC B+ 64k EEPROMs and SW RAM

Post by rmbrowngr » Sun Mar 24, 2019 8:16 am

Which EEPROM’s are compatible for BBC B+ 64k?

I’ve also read a number of solutions on on adding SW RAM including soldering a number of RAM chips together. For sure I understand some fly leads are needed. How would I add 32\64k SW RAM? What’s the definitive answer?
Richard B
Acorn Electrons issue 4 and issue 6 with Master RAM Board, Acorn Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi 2nd Processor, GoSDC MBE with Elk2GoSDC and Cart2GoSDC.
BBC B+ 64K (128K upgraded) with Duel OS

User avatar
danielj
Posts: 7500
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by danielj » Sun Mar 24, 2019 8:24 am

I'd go with Michael's stacked 62256s? They're reasonably easy to get hold of, and it's a pretty straightforward job :) Plus bonus 32k SRAM :D http://www.firths.org/bbc/my_b+128k.html

eprom/eeprom - any of the 32x8 ones (e.g. 28C256) should be OK, but if you want to write in situ you'll have to pick up the write signal from the same place as you do with the sram? I'm not show how the boobip ones are with the B+ (Chris?)
Last edited by danielj on Sun Mar 24, 2019 8:27 am, edited 1 time in total.

cmorley
Posts: 990
Joined: Sat Jul 30, 2016 7:11 pm
Location: Oxford
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by cmorley » Sun Mar 24, 2019 8:49 am

danielj wrote:
Sun Mar 24, 2019 8:24 am
I'm not show how the boobip ones are with the B+ (Chris?)
B only Daniel because of the differences in the way the ROM sockets chip selects are decoded.

User avatar
flaxcottage
Posts: 3721
Joined: Thu Dec 13, 2012 8:46 pm
Location: Derbyshire
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by flaxcottage » Sun Mar 24, 2019 9:47 am

danielj wrote:
Sun Mar 24, 2019 8:24 am
I'd go with Michael's stacked 62256s? They're reasonably easy to get hold of, and it's a pretty straightforward job :) Plus bonus 32k SRAM :D http://www.firths.org/bbc/my_b+128k.html
Absolutely go with this method of adding SWR. It works brilliantly. :D

The B+ also has 32K RAM sockets, which can give you 8 ROMs in the remaining sockets and 6 ROMS in the SWR. That should be enough for anyone's needs. :lol:
- John

Image

User avatar
rmbrowngr
Posts: 315
Joined: Sat Jan 13, 2018 12:46 pm
Location: Dionysos, Greece
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by rmbrowngr » Sun Mar 24, 2019 2:03 pm

I’ve found these instructions as well. https://martin-jones.com/2015/01/18/sid ... o-model-b/ It looks easier, but I don’t know the advantages or disadvantages of these approaches.
Richard B
Acorn Electrons issue 4 and issue 6 with Master RAM Board, Acorn Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi 2nd Processor, GoSDC MBE with Elk2GoSDC and Cart2GoSDC.
BBC B+ 64K (128K upgraded) with Duel OS

User avatar
danielj
Posts: 7500
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by danielj » Sun Mar 24, 2019 2:21 pm

It gives less RAM (32k instead of an additional 96k). It doesn't really look any easier, it's just that you're not stacking chips? Also you're soldering to the motherboard instead of using clips (obviously you can use clips if you like).

User avatar
DutchAcorn
Posts: 2130
Joined: Fri Mar 21, 2014 9:56 am
Location: Maarn, Netherlands
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by DutchAcorn » Sun Mar 24, 2019 3:16 pm

Note for the startup banner to count the memory correctly you need DFS.2.26.

You can also look at this thread: viewtopic.php?f=3&t=9483

To take the memory upgrade one step further you can stack a fourth memory chip and lead pin 20 of that top one to the south pin of S13. This will give you another 32K sideways RAM, but you'll have to place a copy of BASIC in one of the other ROM sockets. See below for a makeshift proof of concept.

Added bonus of this setup is that the startup banner will show "Acorn OS 160K".

BBC B+ Upgraded.jpg
Paul

Image

User avatar
rmbrowngr
Posts: 315
Joined: Sat Jan 13, 2018 12:46 pm
Location: Dionysos, Greece
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by rmbrowngr » Sun Mar 24, 2019 8:43 pm

danielj wrote:
Sun Mar 24, 2019 8:24 am
eprom/eeprom - any of the 32x8 ones (e.g. 28C256) should be OK, but if you want to write in situ you'll have to pick up the write signal from the same place as you do with the sram.
Do you mean this?
Connect the pin 27 ezihook to a source of a write strobe (e.g. pin 24 of the 7002)
Richard B
Acorn Electrons issue 4 and issue 6 with Master RAM Board, Acorn Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi 2nd Processor, GoSDC MBE with Elk2GoSDC and Cart2GoSDC.
BBC B+ 64K (128K upgraded) with Duel OS

User avatar
danielj
Posts: 7500
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by danielj » Sun Mar 24, 2019 8:57 pm

Yup - as they stand the ROM sockets on beebs don't have the write signal hooked up.

d.

User avatar
rmbrowngr
Posts: 315
Joined: Sat Jan 13, 2018 12:46 pm
Location: Dionysos, Greece
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by rmbrowngr » Mon Mar 25, 2019 11:53 am

I’ve also found this topic viewtopic.php?t=9148
Richard B
Acorn Electrons issue 4 and issue 6 with Master RAM Board, Acorn Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi 2nd Processor, GoSDC MBE with Elk2GoSDC and Cart2GoSDC.
BBC B+ 64K (128K upgraded) with Duel OS

User avatar
rmbrowngr
Posts: 315
Joined: Sat Jan 13, 2018 12:46 pm
Location: Dionysos, Greece
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by rmbrowngr » Mon Mar 25, 2019 12:02 pm

I’ve ordered multios for the B+. If this text is correct below you can get SW RAM if configured correctly.
OS 2.00 - The OS from the 64K or 128K BBC Micro B+

DFS 2.26
SRAM 1.05
VIEW A3.0
The Basic Editor 1.32
Advanced Disk Toolkit 2.00 - An extended set of commands for using disks, and for manipulating files between filing systems
EXMON II 2.02 - A machine code monitor to help with debugging assembler routines
Advanced ROM Manager 1.13 - A useful set of commands for managing ROMs, and also building ROM Filing System ROMs
OS 2.00
This image was put together with these ROMs for the more serious programmer in mind. The memory display when this OS is booted will either display 64K, 96K, or 128K, depending on the way links 18 and 19 are set. If they are both set for sideways RAM (to the left), then it will show 128K, if they are both set for mapping to the ROM sockets (to the right), then it will show 64K, and if each is set different, you will get 96K displayed. The SRAM commands, in ADT, ARM and SRAM are useful for creating your own ROM images.

Shadow screen modes are available in OS 2.00, so you have the extended modes 128 through 135, which use shadow memory rather than main memory, freeing up space for your programs. This is the same behavior as the later Master OSs.
Hopefully the postman will deliver this week so I can have some fun with.

BTW, was there ever a plug-in board available which offered SW Ram\Rom? Was there ever something like the integra b?
Richard B
Acorn Electrons issue 4 and issue 6 with Master RAM Board, Acorn Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi 2nd Processor, GoSDC MBE with Elk2GoSDC and Cart2GoSDC.
BBC B+ 64K (128K upgraded) with Duel OS

User avatar
KenLowe
Posts: 696
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by KenLowe » Mon Mar 25, 2019 2:57 pm

I'm not aware of any. There was an official add on board that would take the standard 64k BBC B+ upto 128k, but that would hardly be classed as 'plug in'. There were a bunch of wires that needed to be routed and soldered to various points on the main board. Other reasons why such a board probably doesn't exist:
  1. The BBC B+ is able to handle significantly more ROMs with its on-board 32k sockets than the original BBC could ever cope with, so less of a need for expansion boards. The expansion boards that were produced for the BBC were generally designed to expand them to their full capacity. This is effectively pre-built into the BBC B+
  2. The BBC B+ has a number of SW RAM banks built in, so no need for any expansion to install SW RAM, unless of course you wanted more RAM banks to replace the on-board ROM banks.
  3. The BBC B+ has shadow ram capability built in, so again no need to provide an expansion card for that.
  4. If you ever did want to add an expansion board to the BBC B+, then it would almost certainly be necessary to either de-solder ICs in order to pick up the required data, address and control signals, or add a lot of flying leads between the expansion board and the BBC B+ board to pick up these signals.
  5. Some data, address and control signals are available at the SW ROM sockets, but not everything you might need for your expansion (eg write control, clock signal, ROM select lines etc). By way of comparison, adding an expansion board to the BBC B is much easier, as many ICs are socketed. For example, the IntegraB board simply plugs into the 6502 socket.

User avatar
rmbrowngr
Posts: 315
Joined: Sat Jan 13, 2018 12:46 pm
Location: Dionysos, Greece
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by rmbrowngr » Mon Mar 25, 2019 7:17 pm

If I dream a bit, maybe a nice comprehensive solution could be a board that plugs into the lower set of sockets, has one set of fly leads and provides SW RAM and ROM (EEPROM), a bit like the AP6 for the Electron.

Or go the whole hog with a board to include OS, Basic, DFS 2.26 and ADFS 1.3.
Richard B
Acorn Electrons issue 4 and issue 6 with Master RAM Board, Acorn Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi 2nd Processor, GoSDC MBE with Elk2GoSDC and Cart2GoSDC.
BBC B+ 64K (128K upgraded) with Duel OS

User avatar
rmbrowngr
Posts: 315
Joined: Sat Jan 13, 2018 12:46 pm
Location: Dionysos, Greece
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by rmbrowngr » Fri Apr 19, 2019 1:31 pm

Additional 64k RAM
43253052-562B-477B-9699-B444DDE06DC5.jpeg
8F912626-538B-428F-AE1B-7ED47083F702.jpeg
Only problem now is with the test disk which reports a problem with SRAM. http://8bs.com/othrdnld/manuals/hardwar ... tions2.zip

RAM is showing correctly:
F95460A0-2ED5-49F6-B955-9AF12F77C11B.jpeg
Last edited by rmbrowngr on Fri Apr 19, 2019 1:57 pm, edited 1 time in total.
Richard B
Acorn Electrons issue 4 and issue 6 with Master RAM Board, Acorn Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi 2nd Processor, GoSDC MBE with Elk2GoSDC and Cart2GoSDC.
BBC B+ 64K (128K upgraded) with Duel OS

User avatar
DutchAcorn
Posts: 2130
Joined: Fri Mar 21, 2014 9:56 am
Location: Maarn, Netherlands
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by DutchAcorn » Fri Apr 19, 2019 5:48 pm

Yes, I noticed the same thing: viewtopic.php?f=3&t=9483#p166487

Unsolved mystery?
Paul

Image

User avatar
rmbrowngr
Posts: 315
Joined: Sat Jan 13, 2018 12:46 pm
Location: Dionysos, Greece
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by rmbrowngr » Fri Apr 19, 2019 6:10 pm

DutchAcorn wrote:
Fri Apr 19, 2019 5:48 pm
Yes, I noticed the same thing: viewtopic.php?f=3&t=9483#p166487

Unsolved mystery?
Ahh, yes, I see.

I did load some ROMs successfully.
Richard B
Acorn Electrons issue 4 and issue 6 with Master RAM Board, Acorn Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi 2nd Processor, GoSDC MBE with Elk2GoSDC and Cart2GoSDC.
BBC B+ 64K (128K upgraded) with Duel OS

Coeus
Posts: 1379
Joined: Mon Jul 25, 2016 11:05 am
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by Coeus » Sat Apr 20, 2019 5:48 pm

KenLowe wrote:
Mon Mar 25, 2019 2:57 pm
[*]The BBC B+ has a number of SW RAM banks built in, so no need for any expansion to install SW RAM, unless of course you wanted more RAM banks to replace the on-board ROM banks.
Surely that's only true of the 128K? I am pretty sure for the 64K the extra RAM is shadow RAM and an odd 12K that is not quite a whole sideways RAM bank. From the fact this was on board and the next 64K for SWRAM was on a daughter board it would seem Acorn didn't want to fit SWRAM until it became apparent that if they didn't supply it, someone else would. So yes, in that sense, having an official 128K B+ may have avoided an upgrade board for the 64K.

User avatar
KenLowe
Posts: 696
Joined: Mon Oct 18, 2004 4:35 pm
Location: Scotland
Contact:

Re: BBC B+ 64k EEPROMs and SW RAM

Post by KenLowe » Sat Apr 20, 2019 6:32 pm

I think you're right. The extra 32k of memory that took the BBC B+ to 64k (compared to a standard 32k beeb) was used for shadow RAM (20k) & private RAM (12k). It must have been the additional daughter board (which took the BBC B+ from 64k to 128k), that added the 4 x 16k SWRAM banks.
Last edited by KenLowe on Sat Apr 20, 2019 6:33 pm, edited 1 time in total.

Post Reply