The machines described fall into three groups:
A Tabular summary of the characteristics of each group is given on the following pages.
N. B. The accuracy of these tables is not guaranteed. All information, (particularly prices) should be verified with the manufacturers before any action is based on it.
| Description | Ferranti Mercury | IBM 704 |
|---|---|---|
| Number | Binary Serial 1 Mc digit rate 40 bit words |
Binary Parallel 36 bit words |
| Orders | Single Address 2 orders per word 7 Modifiers |
Single Address 1 order per word 3 Modifiers |
| Arithmetic | Floating point 30/10 10 bit fixed point arithmetic for counters |
Fixed point Floating point 27/9 (?) |
| Times | +- Floating point 180 µs × Floating point 360 µs No Division Red Tape 60µs |
+- Fixed point 24 µs Floating point 100µs ×÷ 24-240 µs Red Tape 24 µs |
| Immediate Access Store | 1024 words on cores | Up to 32,768 words on cores |
| Drums etc Store | Up to 32,768 words on 8 drums, 18 ms revolution time | 8K or 16K words 13 ms access time |
| Magnetic Tape | Yes | Yes |
| Input/Output | Paper Tape, Punched cards and line printer may be available | Punched cards, line printer, CRT |
| Refrigeration | Refrigeration supplied | Elaborate air conditioning required |
| Cost | £100,000 upwards | £500,000 upwards Rental £100,000 upwards |
| Notes | Not suitable for data-processing. Lack of fixed point arithmetic makes difficulties in some programming. Address system inconvenient and confusing, two level store difficult. AUTOCODE makes certain types of problem very simple. | Exceedingly costly by English standards. Large singly level store very convenient for programming. Modification facilities not very convenient . FORTRAN (similar to AUTOCODE) and other routines simplify certain problems. I.B.M. 709 is an improved, faster and still more expensive machine. |
N.B. For both these machines, the cost of a full installation with a reasonable number of tape units, a line printer and other auxiliary equipment would probably be of the order of twice the cost of the minimum machine.
| Description | Elliott Bros. 402E and 402F | English Electric DEUCE | Ferranti Pegasus |
|---|---|---|---|
| Number | Binary Serial 330 Kc digit rate 32 bit words |
Binary Serial 1Mc digit rate 39 bit words |
Binary Serial 330Kc digit rate 39 bit words |
| Orders | 1+1 Address (Optimum Coded 128 words), Source/Function/Destination, Type of order: a'=f(a,s), d'=a, 7 modifiers, 1 order per word | 1+1 Address (Optimum Coded 32 words), Source/Destination, Type of order: (functions are associated with special sources or destinations), No modification, 1 order per word | Two address (Not optimum coded), 7 accumulators, Special counting orders for 2 level store, 7 modifiers (same as accumulators), 2 orders per word |
| Arithmetic | Fixed Point (402F also has floating point) | Fixed Point, Multiplication unsigned (hence usually a subroutine), Mult. and div. are autonomous | Fixed Point |
| Times | +- 204 µs Plus access time for operand and instruction ×÷ 3.4 ms |
+- 64µs Plus access time for operand and instruction ×÷ 2ms |
+- 300µs , No waiting times × 2.0 ms - 5.5ms times |
| Immediate Access Store | 17 words (including acc) | 4× 1 word 3× 2 words 2× 4 words 12 × 32 words (1 ms circulation time) |
55 words (including 7 accs) |
| Drums etc Store | 1024+3968 with relay switching (Revolution time 13ms) Access time 13ms-26ms. No block transfers | 8,192 words (Revolution time 13ms, Transfers take 13-48ms (for 32 words) and are autonomous | 4096 + (1024 isolated) (revolution time 16 ms) Single word or block(8 word) Transfers |
| Magnetic Tape | No | No | Yes at extra cost |
| Input/Output | Paper Tape | Punched Cards | Paper Tape |
| Refrigeration | No (7KVA) | None provided (9KVA) 46 cwt, Some special ventilation may be needed | None provided (12KVA), Some special ventilation needed |
| Cost | 402E £27,000, 402F £36,000 | £43,000 | £45,000 |
| Description | Elliott Bros. 405 | Ferranti Perseus | IBM 650 | Leo Computers LEO II |
|---|---|---|---|---|
| Number | Binary Serial 330 Kc digit rate 32 bit words |
Binary, Coded Binary Serial 330Kc digit rate 72 bit (12 character) word |
Decimal Serial 10 decimal digits (and sign)word |
Binary Serial 525Kc digit rate 19 or 39 bit words |
| Orders | Single address 2 orders per word 2 modifiers |
Single address 3 orders per word 7 modifiers |
1+1 Address(optimum coded) 1 order per word Standard machine has no modifier |
Single Address 1 order per 19 bit word 3 modifiers |
| Arithmetic | Fixed point binary | Binary Accumulator , Variable(mixed)radix acc. | Decimal (fixed point) | Fixed point binary |
| Times | +- .1 ms × ÷ 3.3 ms Plus access (average .76ms) |
+- .39ms × 1-9.5ms. ÷ 3-21 ms (autonomous mult. and div.) |
+- .76 ms ×12 ms ÷ 16.2ms Red Tape .44ms Plus access(av. 2.4ms) |
+- .34ms × .65-3.5ms ÷ 3.5ms Plus access time(average .16ms) |
| Immediate Access Store | 3×1 word + acc, 8to32×l6 words(128-512 words) | 160 × 1 word, 54 × 16 words = 1024 words, Data normally in 1 word lines, programme in 16 word lines. | 3 words (acc etc) | 14 long words, 64 × 32 short words |
| Drums etc Store | Either 4K (revolution time 12.8ms) or 16K (revolution time 25.6ms) | No | 2000 words (main store) (Revolution time 4.8ms) | Up to 65K words on 8 drums Revolution time 11 ms |
| Magnetic Tape | Yes | Yes | Yes | No |
| Input/Output | Paper Tape, Punched Cards, Elec. Typewriter, Magnetic Tape / Paper Tape / Teleprinter / Line printer optional | Paper Tape, Punched Cards, Lineprinter (off line) | Punched Cards, Line printer(off line) | Paper Tape, Punched Cards, Line Printer |
| Refrigeration | None provided | Provided | Elaborate air conditioning necessary | Weight 197 cwt, 40 KVA |
| Cost | According to size £40,000 upward | about £260,000 (with 8 magnetic tape units) | £70,000 upwards | £68,000 upwards |
N.B Relative costs of commercial machines are generally very misleading as the cost of the ancillary equipment(such as magnetic tapes, printers etc, ), are sometimes included and sometimes not. As the cost of these is frequently half the total cost of the installation no valid comparison is possible without an exact knowledge of what is included in the price.
