Friday, 19 October 2018

Wednesday, 17 October 2018

COMAL (Common Algorithmic Language)

COMAL was a programming language first developed in Denmark in 1973 by Borge R. Christensen and Benedict Lofstedt [1]. The language was a structured language and heavily influenced by contemporary popular educational languages including BASIC and Pascal, indeed the intention of the developers of COMAL was to try and combine the simplicity of BASIC with the power of Pascal [2].

What made COMAL stand out was that it was available for 8-bit microcomputers in the late 1970s and early 1980s and was one of the few structured languages available for those computers at the time. Though like a number of "alternative" languages (like Forth on the Jupiter Ace) BASIC proved impossible to dislodge as the language "everyone" had.

COMAL did have some success though and is still used to this day as a teaching language, it was especially popular in Ireland in the 1980s where Apple supplied around five hundred Apple IIs running COMAL-80 to schools. Earlier versions of COMAL had no graphics commands but these were added later on especially to Commodore implementations of the language which included turtle graphics.

Now for some examples of COMAL, if you are familiar with languages like BASIC then COMAL will seem very familiar:

0010 PRINT "HELLO WORLD"

0010 INPUT AMOUNT
0020 PRINT "PLEASE PAY ", AMOUNT

0010 PRINT "HOW MANY TIMES?"
0020 INPUT TIMES
0030 FOR NO:=1 TO TIMES DO
0040  PRINT "HELLO NUMBER ", NO
0050 NEXT NO

[1] John Kelly, Foundations in Computer Studies with COMAL (2nd Edition) (Educational Company of Ireland, 1984) p. vii
[2] Borge R. Christensen, Beginning COMAL (Ellis Horwood, 1982) p. 6

Tuesday, 16 October 2018

Golden Age (14) : Serpents in Eden

A highly enjoyable collection of short-stories featuring Golden Age era (though not necessarily genre) mystery and crime. The theme is crime that takes place in the sleepy hamlet and quiet village but apart from that there is a great variety of story here. Some of the crimes being quite mundane too such as Margery Allingham's "A proper mystery" which involves a trodden down plot at a flower show.

But there are also some rather more serious crimes such as in Ethel Lina White's very atmospheric "The scarecrow" about an escaped madman who is out to kill the woman he failed to before. My favourite though is E.C. Bentley's "The genuine tabard" about stolen historical artefacts and fooling rich Americans to buy them.

Saturday, 13 October 2018

Rickmansworth

Originally I planned to go to Manchester today but the weather in the North West (and Wales) was awful so I headed South East instead and by the time I got to Rickmansworth the rain had stopped and the Sun had come out (and was remarkably warm for mid-October). I walked the Grand Union Canal, I didn't do as much as I intended as I got a blister on my foot but i'll return. Rickmansworth is a nice town in Hertfordshire, deep in what became known as "Metro-Land" to the North West of London. You can see my canal photos here.






Wednesday, 10 October 2018

Jupiter Ace

One characteristic was common to the microcomputers of the late 1970s and early 1980s, they all tended to have BASIC included on a system ROM. Well there was one notable exception, the Jupiter Ace. It was the first home computer to be based on Forth instead of BASIC [1]. The Ace was developed by British company Jupiter Cantab and released in 1982.

Apart from Forth the Ace was quite typical of the period having a Z80A CPU at it's heart and 1KB of RAM (my Mac has four million times as much memory), in terms of form factor it was not unlike the Sinclair ZX81 though a different colour of course and with rubber keys. It also had quite a different internal arrangement though not unlike the Spectrum in some ways (the designers were ex-Sinclair who had worked on the ZX81 and Spectrum).

Forth was chosen as it was considered ideal for a computer like the Ace being fast and compact and a structured language compared to the BASICs of the time. Unfortunately the Ace didn't catch on, the lack of BASIC ended up being a massive hinderance not a bonus. When you are swimming against the flow you need to be really really good and the Ace, despite some nice features, was not. Its graphics were low resolution black and white (64x48) and it lacked decent sound. Forth was also not as easy for beginners to learn compared to BASIC.

For the average home user it was not really that attractive though the inclusion of Forth and the ability to expand the Ace to 51K meant it had appeal to hobbyists. However there were not enough of them to make it a hit.

Around five thousand of the original Ace and eight hundred of the Ace 4000 with an improved case are reported to have been sold. The Ace was discontinued in 1984.

[1] Max Philips, Microcomputer Catalogue (Marshall Cavendish, 1983) p. 14