Search found 822 matches

by dp11
Fri Sep 21, 2018 7:29 pm
Forum: hardware
Topic: What are people happy soldering ?
Replies: 29
Views: 445

What are people happy soldering ?

I'm planning a new little project which I think will create some interest.

I'd like it to be able to fit under a Master, but the master gap too small for the simple easy to solder design so I'm after feedback of the best way to get as much potential users as possible.
by dp11
Sun Sep 09, 2018 8:25 pm
Forum: hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 7
Views: 331

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

IanB wrote:
Sun Sep 09, 2018 8:11 pm
Perhaps we should co-ordinate so that we have one design that works for any 1Mhz bus based project.
Definitely, I'll dig up my notes
by dp11
Sun Sep 09, 2018 1:35 pm
Forum: hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 7
Views: 331

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

I've got some sketches of of a 1MHz to Pi interface, but I haven't done anything more yet.

I wanted to get ADFS Harddrive emulation working
by dp11
Wed Sep 05, 2018 11:26 am
Forum: hardware
Topic: CPLD programming issue
Replies: 8
Views: 136

Re: CPLD programming issue

With the beeb off is there actually 3.3v on the board ? or is voltage regulators internal diode back feeding the 5v rail of the beeb ?
by dp11
Wed Sep 05, 2018 11:05 am
Forum: hardware
Topic: CPLD programming issue
Replies: 8
Views: 136

Re: CPLD programming issue

My guess would be noise on the TCK signal. Try adding some termination e.g. 100R to ground at the CPLD for TCK and or 100pF.
by dp11
Tue Sep 04, 2018 4:29 am
Forum: hardware
Topic: BBC Master Mode 7 corrupted
Replies: 21
Views: 604

Re: BBC Master Mode 7 corrupted

I'd be very surprised if ic21 databus had failed as if the bd bus fails then most of the io doesn't work including the system via so the keyboard won't work.
by dp11
Thu Aug 30, 2018 2:33 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #1 : The ratty one
Replies: 92
Views: 3638

Re: Superbrain #1 : The ratty one

Looks like A0 is shorted to D5 in some way.
by dp11
Mon Aug 20, 2018 4:00 pm
Forum: emulators
Topic: Summary of emulators for 8bit acorns
Replies: 24
Views: 479

Re: Summary of emulators for 8bit acorns

Sounds good :) I'd expect compilation instructions to be on a projects Github page, or wherever, which should always be current. I agree they should be current. It might be nice to actually test them. I've often found some extra library or component is needed and for a newbie this is very off putti...
by dp11
Sat Aug 18, 2018 12:13 pm
Forum: software & utilities for the pc, mac or unix
Topic: BBCSDL - Functional Differences from Other BBC BASIC implementations?
Replies: 49
Views: 816

Re: BBCSDL - Functional Differences from Other BBC BASIC implementations?

+1 to the very recent comments. No need to leave and Thanks for your hard work.
by dp11
Thu Aug 16, 2018 9:19 pm
Forum: software: other
Topic: Designer Castles..
Replies: 23
Views: 519

Re: Designer Castles..

I wonder, does it have protection to prevent in running in SWR ? there was something I had to do to get it to work. I'm pretty sure I had to load multiple swr banks. Was there a later version with a bigger rom ?
by dp11
Wed Aug 15, 2018 7:43 pm
Forum: software: other
Topic: Designer Castles..
Replies: 23
Views: 519

Re: Designer Castles..

A master can have a rom which takes two banks 16K banks.

It was a long time ago so I may have bits wrong.
by dp11
Wed Aug 15, 2018 6:57 pm
Forum: software: other
Topic: Designer Castles..
Replies: 23
Views: 519

Re: Designer Castles..

I don't recall any extra logic . I was using a Master at the time and Masters can take 32K ROMs.
by dp11
Wed Aug 15, 2018 5:52 pm
Forum: software: other
Topic: Designer Castles..
Replies: 23
Views: 519

Re: Designer Castles..

IIRC there is something funny about the ROM ( e.g. 32K ). I have memories of moding it to run from SWR.
by dp11
Wed Aug 15, 2018 10:56 am
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 208
Views: 11665

Re: Open Source Logic Analyzer Experiments

That looks much better it matches : http://mdfs.net/Docs/Comp/BBC/OS1-20/D940
by dp11
Tue Aug 14, 2018 8:07 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 208
Views: 11665

Re: Open Source Logic Analyzer Experiments

realtime USB over a VM can be an issue.
by dp11
Tue Aug 14, 2018 7:42 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 208
Views: 11665

Re: Open Source Logic Analyzer Experiments

Doesn't look right to me. The reset vector on a beeb points to D9CD . Executing code in the FC page is also very unlikely.
by dp11
Sat Aug 11, 2018 6:41 am
Forum: hardware
Topic: Raspberry Pi B+ compatible GPIO Extender 40-way Ribbon Cable Female-Male
Replies: 27
Views: 612

Re: Raspberry Pi B+ compatible GPIO Extender 40-way Ribbon Cable Female-Male

Can you post a screenshot of the text. And how long is the cable.
by dp11
Wed Aug 08, 2018 8:46 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 194
Views: 4004

Re: Z80 Protocol Decoder

sound a bit like you need a protocol encoder to drive signals on to the bus , fire interrupts and clock the cpu. No need for rom or ram
by dp11
Mon Jul 09, 2018 6:46 pm
Forum: emulators
Topic: Ceefax Engineering Test Page - BeebEm 4.13 & B-em
Replies: 67
Views: 11040

Re: Ceefax Engineering Test Page - BeebEm 4.13 & B-em

Clocksp adjust its run time so that very fast cpus don't finish so quickly you end up with a test taking zero time.
by dp11
Sun Jul 08, 2018 11:46 am
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 281
Views: 10734

Re: RGB to HDMI using a Pi Zero and a small CPLD

If glitches do occur then a diode across R119 will speed up the rising edge. If the ls86 is socketed then replacing it with a 74hc86 could also work.
by dp11
Sat Jul 07, 2018 6:26 pm
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 281
Views: 10734

Re: RGB to HDMI using a Pi Zero and a small CPLD

Simply take the video input and feed it through a potential divider. E. G. Video input via R1 to Cpld input. At the junction of of R1 and the cpld connect R2. The other end of R2 could just go to ground but could goto a dac.
by dp11
Sat Jul 07, 2018 5:24 pm
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 281
Views: 10734

Re: RGB to HDMI using a Pi Zero and a small CPLD

You could move the sampling threshold voltage with two resistors. For a dac you can a pwm and and rc filter.
by dp11
Fri Jun 29, 2018 4:08 pm
Forum: off-topic
Topic: Using BBC BASIC to teach programming concepts in 2017
Replies: 93
Views: 2931

Re: Using BBC BASIC to teach programming concepts in 2017

There are a number of solutions

A P C
42 6 52
41 13 46
40 20 40
39 27 34
38 34 28
37 41 22
36 48 16
35 55 10
34 62 4

Notice how P changes by 7 each time and C changes by 6
by dp11
Mon Jun 04, 2018 10:42 pm
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 281
Views: 10734

Re: RGB to HDMI using a Pi Zero and a small CPLD

An option would be to use the spare GPIO signals and TX RX Via Jumpers so that the CPLD can be insystem programmed
by dp11
Sun Jun 03, 2018 8:18 am
Forum: programming
Topic: 12-second Mandelbrot rendering on the BBC Master!
Replies: 107
Views: 3251

Re: 12-second Mandelbrot rendering on the BBC Master!

If I'm right this

Code: Select all

bit #1
    beq left_margin_even
    inc A
    
Can be replaced with

Code: Select all

   Inc a
   And #&fe
Saves a few bytes
by dp11
Sat Jun 02, 2018 8:17 pm
Forum: programming
Topic: 12-second Mandelbrot rendering on the BBC Master!
Replies: 107
Views: 3251

Re: 12-second Mandelbrot rendering on the BBC Master!

The final txa in kernel isn't used in hline or vline (14000ish times) it is used in box (1751 times) so it might be worth in box after calculate_through_cache testing bit 7 of A is it is clear doing ASL A
by dp11
Sat Jun 02, 2018 6:10 pm
Forum: programming
Topic: 12-second Mandelbrot rendering on the BBC Master!
Replies: 107
Views: 3251

Re: 12-second Mandelbrot rendering on the BBC Master!

just a bit of tidying up really in .box lda #&ff sta colourflag I think the lda can be removed before JSR hline there is this bit of code sec lda boxx2 sbc boxx1 sta sidecount This can be moved into hline. similar for vline. bne hline will need to be changed to bne hline_loop. I do wonder if hline c...
by dp11
Fri Jun 01, 2018 10:26 pm
Forum: programming
Topic: 12-second Mandelbrot rendering on the BBC Master!
Replies: 107
Views: 3251

Re: 12-second Mandelbrot rendering on the BBC Master!

I was thinking just one kernel, but two setups. Mandel setup is the longest so that is one block followed by kernel. julia is assembled with a bra to kernel at the end of it. then just swap block over at the start.