Search found 800 matches

by flynnjs
Tue Jul 25, 2017 10:17 pm
Forum: hardware
Topic: Beeb WiFi SD Card
Replies: 9
Views: 1216

Re: Beeb WiFi SD Card

I did try one of the commercial ones in e BeebSCSI but they need to work in proper SD mode
not simple SPI mode (which is what the library BeebSCS uses supports) so no-go.
I would think fairly easy to knock up on an ESP8266 or similar.
by flynnjs
Tue Jul 25, 2017 10:11 pm
Forum: acorn atom and system
Topic: ICE T65/Z80/6809
Replies: 657
Views: 54927

Re: ICE T65/Z80/6809

I haven't seen how the level shift logic works on Godil. Both it and my shifter are basically a pull-up on the 5v side and a FET clamp. This means that it never drives above 3v3 which is OK for TTL (which is LVTTL compatible) but might not work correctly with CMOS. The other problem is software whi...
by flynnjs
Tue Jul 25, 2017 9:51 pm
Forum: acorn atom and system
Topic: ICE T65/Z80/6809
Replies: 657
Views: 54927

Re: ICE T65/Z80/6809

I *think* this might be the right .UCF ... sorry, it was a quick test and I went back to using my GODIL afterwards ... :oops:
by flynnjs
Sat Jul 22, 2017 7:00 pm
Forum: for sale / freebies
Topic: BeebSCSI mini
Replies: 168
Views: 18849

Re: BeebSCSI mini

OK, up to ~20 people now so I'll mark them back in stock on the webshop.
They will be PREORDER as I need to get some more PCBs which will take
some time. Also I have a busy summer so I expect dispatch around mid
September.
by flynnjs
Sat Jul 22, 2017 6:48 am
Forum: acorn atom and system
Topic: ICE T65/Z80/6809
Replies: 657
Views: 54927

Re: ICE T65/Z80/6809

@Mark I meant zero Ohm.
by flynnjs
Fri Jul 21, 2017 6:54 am
Forum: acorn atom and system
Topic: ICE T65/Z80/6809
Replies: 657
Views: 54927

Re: ICE T65/Z80/6809

I knew the adapter board was a pre-emptive strike but I didn't know what the latency would be :mrgreen: I have about 15 more PCBs left from the initial batch. I dont think I have any of the level shifters out there. What I really need is a source of the right-angle pin header as is used on the under...
by flynnjs
Thu Jul 06, 2017 6:38 am
Forum: for sale / freebies
Topic: Offered: Matchbox sized 6502 / Z80 / 6809 Co Pro
Replies: 603
Views: 68861

Re: Offered: Matchbox sized 6502 / Z80 / 6809 Co Pro

Last couple of these available on the webshop now. Once these have gone then
there won't be another batch, even hand built.
by flynnjs
Thu Jul 06, 2017 6:35 am
Forum: for sale / freebies
Topic: BeebSCSI mini
Replies: 168
Views: 18849

Re: BeebSCSI mini

Since ADFS will take quite a bit of resources on a model B I take it that BeebSCSI is mostly targetted for the Master. I fitted one of these to my B+ (in a 32KB socket) and installed DFSE00 and ADFSE00: https://datasheets.maximintegrated.com/en/ds/DS1230AB-DS1230Y.pdf You could do the same in a mod...
by flynnjs
Mon Jul 03, 2017 7:04 pm
Forum: for sale / freebies
Topic: BeebSCSI mini
Replies: 168
Views: 18849

Re: BeebSCSI mini

I shall do another batch but I need to gauge interest, so I'll run a list here for a week or so.
by flynnjs
Mon Jun 19, 2017 4:35 pm
Forum: hardware
Topic: Acorn IC die shots
Replies: 4
Views: 738

Re: Acorn IC die shots

dp11 wrote:The top one doesn't really have enough pads to be anything from the Archimedes I don't think.
I guess, as Ed said, only 27 pads. Seems quite high density and too irregular to be a ULA.
Did Master/Compacts every have anything full ASIC?
by flynnjs
Mon Jun 19, 2017 4:18 pm
Forum: hardware
Topic: Acorn IC die shots
Replies: 4
Views: 738

Re: Acorn IC die shots

I had assumed that the bottom one was possibly a ULA of some type. The other I thought was very processor like or possible processor support IC. They were in the tray with a ceramic quad flat pack with "Engineering Sample" written on the top. This engineering sample was the same size and had the sam...
by flynnjs
Sun Jun 18, 2017 4:36 pm
Forum: hardware
Topic: Domesday86 Project
Replies: 82
Views: 6213

Re: Domesday86 Project

I may replace the micro sd socket with a full size one so that I can drop adfs images on using a wifi-sd card. Disappointingly, this won't work as the wifi-sd cards only boot when connected to an SD host controller in full SD mode and don't work when in SPI mode. Looking at the fat-fs documentation...
by flynnjs
Sun Jun 18, 2017 10:31 am
Forum: hardware
Topic: Help with voltage overload protection on Analogue in
Replies: 29
Views: 2266

Re: Help with voltage overload protection on Analogue in

could anyone explain to me the difference between the 0V pins and the Analogue Ground pins? Pin 8 on the analogue port is connected to 0V on the Beeb motherboard so they are logically the same. However, the AGND pin will be connected in the shortest possible route to the AGND pin of the ADC which i...
by flynnjs
Thu Jun 15, 2017 11:53 am
Forum: hardware
Topic: OS RAM module
Replies: 84
Views: 7253

Re: OS RAM module

cmorley wrote: It seems perfectly happy with either data and/or program in high RAM. You just need to massage LOMEM & HIMEM in the correct order if you want PAGE>LOMEM.
This is not surprising as non HiBasic could be used just this way when copied to the 2nd Proc?
by flynnjs
Mon Jun 12, 2017 12:07 am
Forum: for sale / freebies
Topic: BeebSCSI mini
Replies: 168
Views: 18849

Re: BeebSCSI mini

Yes, I'll be doing some more but I need to get another batch of PCBs in first.
by flynnjs
Sun Jun 11, 2017 6:46 am
Forum: other vintage computer hardware, software and games
Topic: Can someone explain why YUV output doesn't work?
Replies: 6
Views: 1292

Re: Can someone explain why YUV output doesn't work?

It's possible the TV only supports component input at HD resolutions. Best check the TV user manual.
by flynnjs
Fri Jun 09, 2017 8:02 am
Forum: for sale / freebies
Topic: BeebSCSI mini
Replies: 168
Views: 18849

BeebSCSI mini

I'm pleased to announce that I've made up a few BeebSCSI minis and made them available on my webshop. Many thanks to Simon for his design and efforts (see: http://www.domesday86.com/?page_id=400) My version is a direct copy other than using SMD termination resistors and shrinking the PCB so that it ...
by flynnjs
Fri Jun 09, 2017 7:42 am
Forum: hardware
Topic: Acorn IC die shots
Replies: 4
Views: 738

Acorn IC die shots

At the Cambridge meetup, I took these snaps of some wafers that were in a box at the centre.
They are of Acorn heritage but we weren't sure what they might be. Any ideas?
IMG_0854.JPG
IMG_0855.JPG
by flynnjs
Tue Jun 06, 2017 6:19 pm
Forum: for sale / freebies
Topic: Offered: Matchbox sized 6502 / Z80 / 6809 Co Pro
Replies: 603
Views: 68861

Re: Offered: Matchbox sized 6502 / Z80 / 6809 Co Pro

A bit surprised that people were nagging for more of these and when I
do so there is little interest.
by flynnjs
Tue Jun 06, 2017 6:15 pm
Forum: hardware
Topic: Cheap Xilinx LX9 Starter Board
Replies: 19
Views: 3668

Re: Cheap Xilinx LX9 Starter Board

More than £11 in small quantities... £11 plus VAT at least! The adapter worked first time and I got Dave's ICE working on the LX9 so as a minimum was an upgrade and cheaper than the GoDIL which is Spartan 3 based. As for the evolution, it's odd that you ask, because I'd not done anything on it until...
by flynnjs
Fri Jun 02, 2017 7:49 pm
Forum: off-topic
Topic: x86 Internals for Fun & Profit
Replies: 12
Views: 1542

Re: x86 Internals for Fun & Profit

The fastest RAM cells (including L1 cache) are around 1ns.
25 years ago, 386 cache was about 10ns.
And the size isn't much different either.
by flynnjs
Fri Jun 02, 2017 7:23 pm
Forum: hardware
Topic: What to try re-engineering next.....
Replies: 29
Views: 3312

Re: What to try re-engineering next.....

hoglet wrote:The diodes are drawn backwards I think.
Just making sure everyone is awake :)
by flynnjs
Fri Jun 02, 2017 5:07 pm
Forum: off-topic
Topic: x86 Internals for Fun & Profit
Replies: 12
Views: 1542

Re: x86 Internals for Fun & Profit

Actually, evolution beyond original design isn't the main reason CPUs are so complex. It's more down to the fact RAM just hasn't become significantly faster and the complexity is just a load of hacks to try to avoid being held up by RAM. If you like crazy CPU arch then go check out the Mill: https:/...
by flynnjs
Fri Jun 02, 2017 4:21 pm
Forum: for sale / freebies
Topic: Offered: Matchbox sized 6502 / Z80 / 6809 Co Pro
Replies: 603
Views: 68861

Re: Offered: Matchbox sized 6502 / Z80 / 6809 Co Pro

I've made a few more of these available on the webshop.
These will be made to order using the remaining PCBs I have.
by flynnjs
Fri Jun 02, 2017 3:39 pm
Forum: software: other
Topic: Restarting new BASIC program
Replies: 13
Views: 1269

Re: Restarting new BASIC program

A quick check, recursively starting BASIC doesn't appear to overflow the 6502 stack so
BASIC must be resetting it somewhere.
by flynnjs
Fri Jun 02, 2017 3:14 pm
Forum: software: other
Topic: Restarting new BASIC program
Replies: 13
Views: 1269

Re: Restarting new BASIC program

I think the best way to do this which doesn't require calling directly into BASIC internal routines is just to insert a line into the keyboard buffer to set PAGE and RUN, then exit to BASIC. But if my machine code was originally called by BASIC CALL then won't there will still be a call on the stac...
by flynnjs
Fri Jun 02, 2017 9:51 am
Forum: software: other
Topic: Restarting new BASIC program
Replies: 13
Views: 1269

Restarting new BASIC program

If call out from a BASIC program to a bit of machine code which for example
replaced the original BASIC program with some new BASIC, is there any way of
throwing away the BASIC stack and starting again?
by flynnjs
Fri Jun 02, 2017 9:34 am
Forum: hardware
Topic: What to try re-engineering next.....
Replies: 29
Views: 3312

Re: What to try re-engineering next.....

I've been pawing over the schematic for the TWOMEG-128 trying to check that it all looks sane and correct but also trying to figure out how it works. For reference, this is my description corresponding to the schematic in a previous post (which I've just updated): Address decoding: A set of diodes, ...
by flynnjs
Tue May 30, 2017 5:16 pm
Forum: software: other
Topic: Sideways RAM Utilities
Replies: 68
Views: 5963

Re: Sideways RAM Utilities

I also have, though not on-line, a disassembly of the Acorn B+/master SRAM, i.e. that bundled into later version of DFS. I have 1.03 (DFS 2.23) and 1.05 (DFS 2.26) in which I have started to put names to the subroutines. This also includes a table giving corresponding addresses for the two version....
by flynnjs
Tue May 30, 2017 1:32 pm
Forum: software: other
Topic: Sideways RAM Utilities
Replies: 68
Views: 5963

Re: Sideways RAM Utilities

If DFS is in a higher slot than the Manager ROM then it's possible that a physical machine may not even complete startup! Welcome to my hour of headscratching at Cambridge the other weekend. I thought I'd killed my B somehow but I'd put 2.26 in above the standard STL manager 128 ROM. On my todo lis...