80-Bus News


September-October 1983, Volume 2, Issue 5

Page 12 of 67


review manual came bound with one of those pull-on plastic spines. T have no objection to then, I’ve used them myself, but when I opened the manual I found I could not read the start of most lines as they were lost in the binding. Pulling the plastic spine off cured that, but then left me with a pile of loose paper. My alternative method of storing manuals – four-hole punching the pages and storing them in a ring binder – would not be perfect either, as the holes would mutilate some of the text. I measured the left and right margins at 10mm and 15mm respectively. I reckon they should be 15mm at an absolute minimum, 20mm would be better.

On glancing through the Hisoft HP5 manual one thing I noticed immediately was that the range of the floating point numbers was given as 3.4x10 to 5.9x107) . However the range that the Am9511 can handle directly is only 9.221018 to 2.7Tx1 072 . Subsequently I wrote a short program that verified that the limits in HP5 are those of the Am9511.

Support – The area where a product like this stands or falls is in how easy it is to use. All your current software will obviously ignore it, and it is nota trivial task to get round this problem. Belectra have taken a step in the right direction by ineluding in the price a special version of the Hisoft Pascal compiler whose run-time routines make specific use of the arithmetic processor. So if you want to "nlug-in-and-go", you are currently restricted to Hisoft Pascal, or Pascal/MT+ which also has an option for using the Am9511.

Trying it out

I list below a few comparitive_ benchmarks of the performance. A nice benchmark I came across recently [4] is a good test of processor speed and accuracy on purely arithmetic routines. This very nicely matches the area in which the HSA-88B would be used. Try it on your current favourite interpreter and/or compiler for comparison with the figures below. Ideally it should produce a result of 2500 in as little time as possible.

5 REM Benchmark from DDJ No 83 (Sept ‘83) p120-122

10 N%=2500

20 A=1

30 FOR I%=1 TO N&-1 : A=TAN(ATN(EXP(LOG(SQR(A*A)))) )+1:NEXT 1% 40 PRINT USING "A=££££.££LL"5A

Fig 1 – DDJ Benchmark in BASIC Language Result Time

Standard MBASIC interpreter: 2304.86 in 225 secs

BASCOM compiler : 2304.86 in 183 secs *Modified MBASIC interpreter: 2326.94 in 41.8 secs Am9511 support Hisoft Pascal (V5) : 2326.94 in 29.1 secs " " Simple assembly code : 2326.94 in 26.8 secs " " version of the benchmark

* gee below Fig 2 – Benchmark timings (4MHz Z80)

Unfortunately several Pascals do not appear to offer TAN as a function, (they do have SIN and COS), and only have ARCTAN for the inverse functions. So, for the Pascals, I have translated the PCW BMS into Pascal.

This is an OCR’d version of the scanned page and likely contains recognition errors.

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