1⟩ Explain When did you build the prototype?
Summer holidays, 1978. Then I went home and drew circuit boards on the dining room table (and floor!) and wrote the manual. All by hand, of course.
Christmas 1978 I must have written System BASIC.
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2⟩ Explain Was the design based on/derived from an earlier machine? Kim-1, Apple I, etc?
Not exactly based on anything. Most of its heritage was from an automated cow feeder that Id designed for a Harrogate company the previous summer (1977). Quite an advanced thing, really it had a (waterproof) number pad, big 7 segment LEDs, OS in non-volatile EEPROM, and the trademark 6502. Both were from my own designs for something for myself, and they came from the aether.
The most hair-raising thing was the cow-feeders programme. I didnt own a PROM blower, so I had to write the whole thing by hand and send it off to a company who hand entered it into a machine and sent me back the PROM. That worked first time, too. Mind you, it was even smaller, being a boot loader that allowed the cow-feeders EEPROM to be initialised.
3⟩ Explain How did the Acorn Microcomputer get started?
I had designed something similar for myself, and was in the process of helping Hermann [Hauser] with his ideas for an electronic pocket book (what we might nowadays call a PDA). In the course of showing that my designs for it would work, I showed him my schematics for my own machine and was challenged to build it. So I did With my own white ceramic 6502, too. That was just the equivalent of the CPU board of the System 1 with LEDs and keyboard (all on the same bit of Veroboard) the cassette interface was added later. I think Hermann was overly impressed when it worked first time!
4⟩ What is the Acorn System 1?
Packing them in boxes (upstairs at 4a Market Hill): the whole company would stand around tables (a production square) and put in the right components (me, Hermann, Hermann?s then fianc? Stephen, Chris). We all did pretty much anything: I ended up as Hermann?s secretary before we could afford one!
There used to be problems with answering the phone: one chap would ring up and say ?I have got an Acorn, it does not work? often enough for it to become a legend. We got very tired of kits ? the highlight being a guy who assembled his Atom with glue because he knew that heat (solder) would damage them ? so that coloured the BBC machine a lot.
5⟩ Explain When was the last Acorn System x shipped?
We designed the BBC machine using System 3s (I did a lot of character design work with a prototype System 80 column video card) and still had System 4/5 stuff going on in 1982 perhaps then.
6⟩ What is no bugs in the monitor program?
No bugs in the first, smaller, version of the software (256 bytes of code blown into PROM by Nick Toop?s PROM blower). There were a couple of problems with the cassette interface software because I got the order of bits the wrong way round (from the CUTS? standard). But hey, it was only 512 bytes: you can?t make any mistakes in that even when you write it by hand, hand assemble it and hand enter it into the PROM blower! Besides, it could debug itself to a fair extent (given that it basically worked).
7⟩ Which are the key design issues of a computer Network?
★ Connectivity
★ Cost-effective Resource Sharing
★ Support for common Services
★ Performance
8⟩ What is Unicasting?
If the message is sent from a source to a single destination node, it is called Unicasting.
9⟩ List the names of layers which are network support layers?
★ Physical Layer
★ Data link Layer and
★ Network Layers
10⟩ What is Multiccasting?
If the message is sent to some subset of other nodes, it is called Multicasting.
11⟩ What is Broadcasting?
If the message is sent to all the m nodes in the network it is called Broadcasting.
12⟩ List the typical elements of a process image?
User data:
Modifiable part of user space. May include program data, user stack area, and programs that may be modified.
User program:
The instructions to be executed.
System Stack:
Each process has one or more LIFO stacks associated with it. Used to store parameters and calling addresses for procedure and system calls.
Process control Block (PCB):
Info needed by the OS to control processes
13⟩ Define FDM?
FDM is an analog technique that can be applied when the bandwidth of a link is greater than the combined bandwidths of the signals to be transmitted.
14⟩ Tell me what else do you remember about the Acorn System 1?
Packing them in boxes (upstairs at 4a Market Hill): the whole company would stand around tables (a production square) and put in the right components (me, Hermann, Hermann?s then fianc? Stephen, Chris). We all did pretty much anything: I ended up as Hermann?s secretary before we could afford one!
There used to be problems with answering the phone: one chap would ring up and say ?I have got an Acorn, it does not work? often enough for it to become a legend. We got very tired of kits ? the highlight being a guy who assembled his Atom with glue because he knew that heat (solder) would damage them ? so that coloured the BBC machine a lot.
15⟩ Tell me why did you use the RAM I/O chip, instead of a UART or something similar, when the machine had separate RAM?
Science of Cambridge used 8154s on its MK14 kit (National SC/MP based) and so they were available when we needed something for the 6502. They were fairly cheap and the extra RAM was a bonus, even though it meant converting from 6502 clock/write to the read strobe/write strobe that they used.
16⟩ Tell me was the design based on/derived from an earlier machine? Kim-1, Apple I, etc.?
Not exactly based on anything. Most of its heritage was from an automated cow feeder that I?d designed for a Harrogate company the previous summer (1977). Quite an advanced thing, really ? it had a (waterproof) number pad, big 7 segment LEDs, OS in non-volatile EEPROM, and the trademark 6502. Both were from my own designs for something for myself, and they came from the aether.
The most hair-raising thing was the cow-feeder?s programme. I didn?t own a PROM blower, so I had to write the whole thing by hand and send it off to a company who hand entered it into a machine and sent me back the PROM. That worked first time, too. Mind you, it was even smaller, being a boot loader that allowed the cow-feeder?s EEPROM to be initialised.
17⟩ What is DDks?
DDks are device driver kits, which are equivalent to SDKs for writing device drivers. Windows NT includes DDks.
18⟩ How did Acorn Microcomputer get started?
I had designed something similar for myself, and was in the process of helping Hermann [Hauser] with his ideas for an ?electronic pocket book? (what we might nowadays call a PDA). In the course of showing that my designs for it would work, I showed him my schematics for my own machine and was challenged to build it. So I did? With my own white ceramic 6502, too. That was ?just? the equivalent of the CPU board of the System 1 with LEDs and keyboard (all on the same bit of Veroboard) ? the cassette interface was added later. I think Hermann was overly impressed when it worked first time!
19⟩ Tell me why did you choose to design the computer around the MOS Technologies 6502 microprocessor?
Because it was there. Because it was new. Because a few of the other members of the Cambridge University Processor Group [CUPG] were going on about it being easier to interface to circuits. I guess I don?t really know precisely why I chose the 6502 ? maybe we just had an affinity!
It cost quite a lot back in 1977/78 when I bought mine ? which was a wonderful white ceramic part with gold (coloured?) legs and lid.
20⟩ Tell me what has triggered need for multitasking in PCs?
Increased speed and memory capacity of microprocessors together with the support fir virtual memory and Growth of client server computing.
