Search found 3090 matches

by jgharston
Sat Jul 14, 2018 11:39 am
Forum: hardware
Topic: Electron +Plus 1 + AP5 + MMFS question(s)
Replies: 8
Views: 201

Re: Electron +Plus 1 + AP5 + MMFS question(s)

If you have two different Plus1 support ROMs plugged in you will get problems, as they'll be fighting each other.
by jgharston
Fri Jul 13, 2018 10:45 pm
Forum: software: other
Topic: trying to track down a one-line game, possibly called "One Line"
Replies: 24
Views: 748

Re: trying to track down a one-line game, possibly called "One Line"

Here's the full documentation: ------------------------------------------------------------------------------- Program : MiniLOGO Purpose : One-line Implementation of LOGO Turtle Graphics Author : (C) Jon Ripley, 1999-2001 Version : 0.08 (24th August 2001) -------------------------------------------...
by jgharston
Fri Jul 13, 2018 10:36 pm
Forum: hardware
Topic: Electron +Plus 1 + AP5 + MMFS question(s)
Replies: 8
Views: 201

Re: Electron +Plus 1 + AP5 + MMFS question(s)

You could get that effect if something tramples on the ROM Manager workspace in page D. I've had a quick look through the MMCFS code on GitHub and nothing leaps out.
by jgharston
Wed Jul 11, 2018 10:01 pm
Forum: software: other
Topic: trying to track down a one-line game, possibly called "One Line"
Replies: 24
Views: 748

Re: trying to track down a one-line game, possibly called "One Line"

One-line LOGO: 1 MODE0:VDU28;31,6479;29,640;512;:PLOT69,0,0:REPEATINPUTLINE">"A$:FORX=1TOVALA$:B$=A$:REPEATC=ASCB$AND31:N=VALMID$(B$,2):IFC=3RUNELSEIFC=10ORC=28OSCLIB$:B$="":UNTILFALSEELSEPLOT4*-(C=8),0,0:P=PEOR-(C=16):A=(A-N*(C=18)+N*(C=12))MOD360:D=N*(C=2)-N*(C=6):PLOT1-P,D*SINRADA,D*COSRAD(A+.1):...
by jgharston
Wed Jul 11, 2018 9:42 pm
Forum: programming
Topic: Files created by OPENOUT
Replies: 4
Views: 257

Re: Files created by OPENOUT

Dreamland Fantasy wrote:
Wed Jul 11, 2018 7:36 pm
Are there any technical details of the file format used by files created using the OPENOUT command function?
Any files created by any method have no format, they are pure binary. Any internal format of the binary data is entirely and completely down to the programmer chosing what to so with it.
by jgharston
Tue Jul 10, 2018 10:25 pm
Forum: software: other
Topic: Acorn CP/M disc format
Replies: 1
Views: 100

Re: Acorn CP/M disc format

Coeus wrote:
Tue Jul 10, 2018 6:26 pm
I notice Acorn CP/M format discs have a fake DFS catalogue at the start on side 0.
...
Shouldn't there be a similar fake catalogue for side 2, though?
Nope, 'cos that would end up being in the middle of a CPM file.
by jgharston
Tue Jul 10, 2018 10:21 pm
Forum: software: other
Topic: CP/M Hard Disc BIOS
Replies: 1
Views: 87

Re: CP/M Hard Disc BIOS

Questions, probably for JGH: Disc http://mdfs.net/Mirror/Image/AcornCPM/JGHCPM1.zip is a CP/M bootable disc with a hard disc BIOS. 1. Does this make any assumptions about the disc interface, i.e. SCSI or IDE. No, it just accesses a disk image through the normal OPEN/GBPB/CLOSE interface. 2. Does it...
by jgharston
Tue Jul 10, 2018 10:10 pm
Forum: software: other
Topic: CP/M text Editor Required
Replies: 9
Views: 244

Re: CP/M text Editor Required

Ooo, and it doesn't like text lines terminated with LFs. I should update the text files on my CPM disks that slipped through.
by jgharston
Tue Jul 10, 2018 9:49 pm
Forum: software: other
Topic: CP/M text Editor Required
Replies: 9
Views: 244

Re: CP/M text Editor Required

Coeus wrote:
Tue Jul 10, 2018 4:16 pm
Further to my last post, here is a disc (in Acorn CP/M format, so ready to go on Z80 2nd proc) with VDE configured for the BBC micro,
Note that that attached file is actually a sequential image, which usually has a .ssd extension, not an interleaved image as suggested by the .dsd extension.
by jgharston
Tue Jul 10, 2018 4:10 pm
Forum: software: other
Topic: CP/M text Editor Required
Replies: 9
Views: 244

Re: CP/M text Editor Required

I've used, I think it was, WordStar. You need to run a config program to set the VDU control characters, eg UP=CHR$11, cursor=CHR$31,X+0,Y+0, etc.
by jgharston
Mon Jul 09, 2018 8:03 pm
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 288

Re: BASIC FOR loops

I mentioned in another thread in which a Mandelbrot program in BASIC was included that brandy basic does not handle FOR loops where a NEXT statement occurs for anything other than the innermost FOR loop. I had a look in original BBC Micro User guide and it advises against "bady nested" FOR loops bu...
by jgharston
Sun Jul 08, 2018 6:15 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG Cambridge Sept 7th-9th 2018 BOOKING THREAD
Replies: 60
Views: 1867

Re: ABUG Cambridge Sept 7th-9th 2018 BOOKING THREAD

I was doing some tweeks to PDP11 BASIC, so swapped from my PiTube to my MatchBox to use the PDP11 CoPro, and it seems to have bitrotted or something. The only CoPros that start up are the four 6502 ones. Will there be somebody at Cambridge who can reprogram it? Ta. This is the main reason I've got s...
by jgharston
Sun Jul 08, 2018 2:49 pm
Forum: software: other
Topic: Help needed: M128, PiTubeDirect, Datacentre and GEM 2
Replies: 19
Views: 399

Re: Help needed: M128, PiTubeDirect, Datacentre and GEM 2

I'm guessing it's telling me I don't have enough memory as this is a 128 not a 512, but I wondered if there was a way around this either with a bit of trickery from the datacentre or the PiTubeDirect. When I boot up I get it reporting 80286 with 960k. Any advice would be greatly recieved. Having an...
by jgharston
Sat Jul 07, 2018 12:41 pm
Forum: off-topic
Topic: How to make a battery motor run at different speeds?
Replies: 9
Views: 203

Re: How to make a battery motor run at different speeds?

Yes, I remember at college (years 'n' years go!) experimenting with controlling the speed of AC and DC electric motors and finding stalling points below certain speeds and above certain loads.
by jgharston
Sat Jul 07, 2018 6:58 am
Forum: off-topic
Topic: How to make a battery motor run at different speeds?
Replies: 9
Views: 203

Re: How to make a battery motor run at different speeds?

The speed of a DC motor is proportional to the supply voltage (actually, current), but practical physics gets in the way. Nope. Back EMF is proportional to speed. So it follows that speed is proportional to supply voltage. Torque is proportional to current. Yes, as I was typing that a nagging voice...
by jgharston
Fri Jul 06, 2018 8:32 pm
Forum: off-topic
Topic: How to make a battery motor run at different speeds?
Replies: 9
Views: 203

Re: How to make a battery motor run at different speeds?

The speed of a DC motor is proportional to the supply voltage (actually, current), but practical physics gets in the way. As the windings are disconnected every 180 degrees to reverse the current, the motor relies on inertia to "throw" the rotor (rotating part) past the disconnect/reconnect position...
by jgharston
Wed Jul 04, 2018 2:02 am
Forum: programming
Topic: BBC Changing Coordinate system from 0-1024,0-1280
Replies: 12
Views: 665

Re: BBC Changing Coordinate system from 0-1024,0-1280

A quick bit of testing gives these speeds on 6502 BASIC looping 1000 times: BASIC IV BASIC II NX%=MX%*4+MX%DIV2 -> 255cs 282cs NX%=MX%*4+MX%DIV2+MX%DIV14 -> 298cs 440cs NX%=MX%*4.57 -> 283cs 423cs SX=4.57, NX%=MX%*SX -> 180cs 309cs (SX set outside the loop) So, the fastest in BASIC IV is to store th...
by jgharston
Wed Jul 04, 2018 1:44 am
Forum: programming
Topic: BBC Changing Coordinate system from 0-1024,0-1280
Replies: 12
Views: 665

Re: BBC Changing Coordinate system from 0-1024,0-1280

It's from an Apple II system that I understand is 280×192 with a BASIC coordinate system to match, but 0,0 being top left. Quickly scaling Y from 192 to -1024 can be done with (MY%*5+MY%DIV3)EOR1023 . Scaling X with MX%*4+MX%DIV2 goes from 280 to 1260, leaving 20 logical pixels/4 physical pixels un...
by jgharston
Tue Jul 03, 2018 4:59 pm
Forum: programming
Topic: BBC Changing Coordinate system from 0-1024,0-1280
Replies: 12
Views: 665

Re: BBC Changing Coordinate system from 0-1024,0-1280

8310MOVE MX%*4.5,1023-(MY%*5.1) That seems to be a wierd coordinate size you're converting. The source appears to be 285x-200. Using integer arithmetic would speed it up: MX%*4+MX%DIV2, (MY%*5+MY%DIV8)EOR1023 A more normal "foreign" screen size is 256x200, which is quickly scaled with: MX%*5, MY%*5...
by jgharston
Sat Jun 30, 2018 11:29 pm
Forum: general
Topic: New BeebWiki articles
Replies: 36
Views: 5572

Re: New BeebWiki articles

The following articles in the BeebWiki were recently updated: * Reading command line * Passing a parameter to a language * Returning exit code * Number output in 6502 machine code * Setting Clearing and Copying bits of data * Denormalising a number * What BASIC is running * INKEY * OSBYTE &81 * Syst...
by jgharston
Sat Jun 30, 2018 11:12 pm
Forum: programming
Topic: Passing a flag to language ROM entry point
Replies: 3
Views: 131

Re: Passing a flag to language ROM entry point

Just typed up for the Wiki.

I've observed this method used in about a dozen ROM languages. There's also a more complicated method that lets your language read a free-form parameter line, but I'll have to dig out some disassembled source to get it right.
by jgharston
Sat Jun 30, 2018 10:39 pm
Forum: programming
Topic: Passing a flag to language ROM entry point
Replies: 3
Views: 131

Re: Passing a flag to language ROM entry point

The way to do this is to use OSBYTE 1. Your *command writes its data to OSBYTE 1, and your language startup reads it. .L8000:JMP Language .L8003:JMP Service ... .Service4 \ Gets to... .mycommand JSR ParseNumber:TAX:\ X=8-bit parameter LDA #1:JSR OBYTE :\ Set user/return code LDX &F4 :\ X=my ROM numb...
by jgharston
Thu Jun 28, 2018 11:58 pm
Forum: programming
Topic: Assistance required - Using RNDX (BBC Micro)
Replies: 7
Views: 288

Re: Assistance required - Using RNDX (BBC Micro)

(snip) .rndxtest LDA &6 \ HIMEM lo STA &4 \ save in &4 LDA &7 \ HIMEM hi STA &5 \ save in &5 That's not "saving" HIMEM in 4/5, it's clearing the stack pointer in 4/5 by setting it to HIMEM. If comments lie like this it's no wonder the code can't be understood. Presumably there's a reason to clear t...
by jgharston
Thu Jun 28, 2018 12:16 pm
Forum: software: other
Topic: Expanding BBC BASIC on Acorn 8 bit machines
Replies: 21
Views: 533

Re: Expanding BBC BASIC on Acorn 8 bit machines

64K strings on an 8-bit processor is very difficult as you need somewhere to put a 64K string accumulator.... So how exactly do you think BBC BASIC for Windows and BBC BASIC for SDL 2.0 support 32-bit-length strings? Do you imagine they each have a 4 Gbytes 'string accumulator'? (For the avoidance ...
by jgharston
Thu Jun 28, 2018 9:54 am
Forum: software: other
Topic: Expanding BBC BASIC on Acorn 8 bit machines
Replies: 21
Views: 533

Re: Expanding BBC BASIC on Acorn 8 bit machines

Elminster wrote:
Thu Jun 28, 2018 9:12 am
Richard R:
1. 65535 strings (or some increase from 255)
64K strings on an 8-bit processor is very difficult as you need somewhere to put a 64K string accumulator....
by jgharston
Tue Jun 26, 2018 5:08 pm
Forum: emulators
Topic: Beebem Mode 7 glitch
Replies: 37
Views: 1053

Re: Beebem Mode 7 glitch

My engineering test page I downloaded from the broadcast page 199 in about 1985 with the Teletext Adapter, so it's whatever *CH2, *PAGE 199, *TRANSFER 7000, *SAVE P199 7000+400 gave, with bit 7 stripped except for control codes, and bytes 920-1023 cleared, with this code: 830 DEFFN_5:CLS:PRINT'"…Tra...
by jgharston
Tue Jun 26, 2018 4:49 pm
Forum: emulators
Topic: emulator cycle vs walclock vs TIME accuracy
Replies: 8
Views: 481

Re: emulator cycle vs walclock vs TIME accuracy

I am sure I have seen something to say that the 2Mhz reference for this program is with interrupts disabled. If you have them enabled you would expect the result to be slighly under 2Mhz. When changing what speed tests ClockSp tests did you actually LIST the program? 340 REM This is calibrated agai...
by jgharston
Tue Jun 26, 2018 4:46 pm
Forum: emulators
Topic: emulator cycle vs walclock vs TIME accuracy
Replies: 8
Views: 481

Re: emulator cycle vs walclock vs TIME accuracy

I was playing with JGH's clocksp benchmark and noticed that the string manipulation test was spending a lot of time doing floating point divs so I tweaked it to pre-compute the LEN/2 and LEN/4 constants... Errr... it's doing that to specificially do lots of string operations, *including* timing the...
by jgharston
Sun Jun 24, 2018 11:35 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 394

Re: Floppy / Stiffy Drive setup

1. Would a BBC Master default to 40 or 80 track or must I always set it to the correct tract parameters via a *Drive 0 xx type of command? It defaults to neither, single-steps, using whatever the drive itself is set to. If you've set the drive to double-step, then the drive will double-step regardl...
by jgharston
Sat Jun 23, 2018 4:03 pm
Forum: off-topic
Topic: Using BBC BASIC to teach programming concepts in 2017
Replies: 82
Views: 2251

Re: Using BBC BASIC to teach programming concepts in 2017

I also checked out what the Montessori thinking is on computers. It seems to be to keep children under 12 away from computers, then to use them to teach typing skills, and in the final stages of school to use computers for research and essay writing. I have my doubts about Montessori, but it is at ...