32

Elite used procedural generation. There's a good description of the algorithm on the Elite Wiki and although the original 6502 source code archives are available on Ian Bell's Elite site he also converted the procedural generation code into C for "Text Elite", so that's probably easier to read. This extract from the book "Backroom Boys: The Secret Return Of ...


29

Per Sophie Wilson: To prove that [Steve had] designed the microarchitecture correctly, he wrote, in BBC BASIC, a model of the microarchitecture. To prove that I'd designed the architecture correctly, I wrote an interpreter for the processor's instruction set and wrote programs in it. So, well before any actual commitment to doing things, we could ...


26

First of all, the vast majority of BBC Micros were supplied with a switch mode power supply, but in actual fact anecdotal evidence suggests that the few that did have linear power supplies are actually more reliable, as the switch mode power supplies almost universally have required component replacements by now, but it seems at least some of the linear ...


26

There are a number of optimisations which, in aggregate, will improve performance somewhat: There are multiple linked lists for the variables, one per first letter of the variable name. This makes name lookup faster compared to a more typical implementation with one linked list. The integer variables @% through Z% have fixed memory locations and do not ...


24

This page describes one of the prototype A500s used by Paul Fellows (who led the team in charge of developing Arthur, the operating system which eventually became RISC OS). Paul Fellows himself said This machine is the one I used for development of the Operating System at Acorn. Originally these machines were hooked up to BBC micros via an umbilical into ...


23

Sideways ROM (also RAM in later models) was paged into the processor's address space. Sideways memory sat in the address range from $8000 to $BFFF. The BBC Model B had four slots on the motherboard into which EPROMs could be put to occupy this space. One of the slots was reserved for BBC Basic. Expansion boards could be purchased to expand this to 16 ...


17

Reading up on various preservation efforts, including the Center for Computing History's, and information collected on Andy Finney's and Adrian Graham's sites, it appears that the most difficult part would be physically reading the disks — the required drives were built in limited quantities. If you have one of the drives, it might be possible to connect it ...


16

The Tube interface was intended to enable the addition of what was known as a Second Processor. Although this was something of a misnomer as the additional processor became the main CPU of the system and the base BBC Micro became an I/O controller. When running, the second processor's memory was addressed from &00000000 upwards, and the I/O processor's ...


15

Devices connected to the Tube weren't terribly common because they added further expense to an already rather expensive computer in the first place. The 6502 second processor was £200 and the Z80 was £300, which is about £600 and £900 respectively in 2017 money. Hardware-wise, it consisted of a short bidirectional FIFO used for passing messages between the ...


15

The chips on the motherboard were quite widely spaced. This is still a design consideration when making boards more heat tolerant. Also, the chips didn't generate the sort of heat that more modern, faster processors do. Air did circulate through the BBC case. Entering through the ports on the underside and leaving via cooling slots at the back. There ...


14

Linear power supply was not a BBC engineering requirement by the time I joined Designs Dept in late 1981. Perhaps it was dropped well before actual production; I don't know if that was pushback from Acorn or experience with a prototype. But by late 1981, shipping some with linear PSUs was an unhappy compromise caused by : (a) demand much higher than ...


14

The BBC Micro's specification was drawn up by the BBC (with some subsequent modifications). Computer manufacturers were invited to design a computer system that would meet that specification, and Acorn had an early prototype for their Proton computer that they were able to adapt to suit the BBC. The specification includes: Video display: Either (a) an ...


12

Most hobbyists put a ZIF socket onto those pins. This then was connected through to the sideways ROM sockets on the motherboard. The socket enabled you to insert language ROMs as required, thus not using all the available sideways sockets. However, the main purpose was to fit the Speech Synthesizer unit. Fitting this required modifying both the main ...


9

With all these 'or' in between and jumping between various points, requirements and conclusions, it's a bit unclear what your're looking for. If this is about most colour with least memory, then the (unofficial) modes Mode 8 and Mode 13 are your thing. Or was it a limitation of bandwidth with the 6845 chip that couldn't handle both 320 horizontal pixels ...


8

Well, the folks from stardot came through! It seems it's called Asterisk Tracker, and was published in the December 1984 issue of Beebug magazine. The author was N. Silver: 1L=0:REP.L=L+3:MO.4:DR.1279,0:DR.1279,452:MOVE1279,572:DR.1279,1023:DR.0,1023:F.I=1TOL:V.31,RND(32)+5,RND(31),42,30:N.:P.(L-3)/3:X=0:Y=512:REP.PL.69,X,Y:X=X+4:Y=Y-(INKEY-74+.5)*8:U.PO.X,...


8

Yes. The BBC has a Motorola 6845 generating its screen addresses. That's a flexible chip, with which the developer has wide control over screen sizing and placement. The Electron has a custom ULA designed by Acorn to produce the same video address generation as the 6845 when configured in one of the built-in modes but its functionality is fixed. So on a ...


8

Seemingly predating that StarDot thread by a few years, I found this list of documents that includes "HardwareSpecification.txt", "BASICOutline.txt" and a few others that are "(c) Copyright BBC 1981" rather than copyright Acorn, or dated 1982 when the BBC Micro actually appeared. There are various details not from the StarDot thread, including: unused gate ...


8

Some popular expansion pack features: Programming languages (e.g. BASIC, D-DOS) File managers Office suites (e.g. View, Inter-Chart, Wordwise Plus) Hardware drivers (e.g. Epson Printmaster) Development Utilities Emulators Modems (e.g. Master Modem) Further reading: Chris' Acorns: BBC and Master ROMs


7

PAGE and HIMEM are what you might call "system variables" in BBC basics, they mark the bottom top of the memory available for Basic use, they are intiialised from OS-provided values but can be changed by the user. On a regular BBC micro HIMEM will point to the bottom of screen memory, so it can change if you change screen modes (this BTW meant you couldn't ...


6

The “ashtray” was supposedly meant for serial PROM cartridges, but was often modded for other purposes. Cartridges were becoming rarer by the time the BBC Micro was released, though, and regular EPROMs became the medium of choice. ISTR the Acorn Speech Synthesizer used some hardware in or around that slot.


6

The descriptions are computed via the method goat_soup which works recursiveley. The system description is set by mySystem.description = goat_soup("\x8F is \x97.",&mySys); The description string contains two special characters, \x8F and \x97. Within gout_soup the available set of words and sentences is stored as desc_choice. The special characters are ...


6

It is possible to read the discs using the original Philips player and connecting it to a PC but it requires a low level SCSI driver to be written as the communication is so slow and would time out using the standard comms. The other option is to look at the Domesday86.com project that is trying to sample the discs using a standard laserdisc player by ...


6

I don't know how cleanly memory adopts a default state upon battery failure but even at worst you can still use the machine almost as normal: hold down R while switching on to reset the CMOS RAM. You'll be told that it is reset and prompted to press break for a warm reboot, at which point you should be back to factory defaults and safe at least until your ...


6

In Econet, using synchronous serial transmission, the sender provides the clock together with the data. The receivers need to synchronize with that clock. And the network clock doesn't (necessarily, although it might be somehow derived from the same clock) need to be connected in any way with the system clock. In the BBC Micro, this clock (and the whole ...


6

Econet networking was first developed for Acorn's System line, which had a 6502 CPU clocked at 1MHz. It was later used in their ARM-based Archimedes machines with 8-25MHz CPUs, as well as the RISC PC line which pushed into the hundreds of MHz. So the system clock clearly doesn't need to be identical for all stations on the network. There is, however, ...


5

The 64KB of RAM for the 65C102 co-processor is provided by eight MB8264 64k x 1-bit chips. Each chip provides one bit of memory for every address, meaning that all eight chips are used for every memory location. In many instances, the failure of a RAM chip will affect all memory locations (including the 6502's page 0 registers), meaning that the co-processor ...


5

The cartridge port first appeared on the Electron's Plus One expansion; those on the Master vary the meaning of a few pins but are mostly compatible — ROMs should work without modification (subject to the software, of course), but hardware is likely to be machine specific. The full pinout, including documentation of the machine differences, is contained in ...


5

Whilst researching the 65C102's memory layout, it occurred to me that, since the I/O processor's memory is mapped to 0xFFFFxxxx, Well, that's only a convention set by the filing system. In reality they are two seperate memory spaces, each with 64 KiB (*1). Communication between the Memory blocks is only available under programm controll by both CPUs via a ...


5

No, they where neither rare nor expensive in 1982. Already in 1981 Apple did fit by default 250ns 4116 (usually AMD) to the Apple II+. Since the machine only needed 450ns RAMs, it's safe to assume that there wasn't any noticable price difference. I just checked several II and II+ and only one from ~1978 got 450ns RAM and another from ~1979 or 1980 got 300ns ...


5

Given all of the above [now below], how did it avoid overheating? Short answer: Not enough heat produced in the first place. Long read: (as usual only basic physics needed). (Standard Disclaimer: I hope I did remember all the formulas right, didn't add (many) calculation errors and most important picked the right English words.) Heat in a device only ...


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