V20 vs 8088 Speed Test?

Hardware questions and modifications

Re: V20 vs 8088 Speed Test?

Postby jmetal88 » Wed Jul 05, 2017 5:29 am

Trixter wrote:I had a chance to run actual numbers using TOPBENCH on a PCjr with a memory expansion, and the same PCjr with an NEC V20 added. With no other differences, here's what the numbers look like:

Code: Select all
+--------------------------------------+-------+-------------+-------------+------------+-----------+-------------+--+---------+
|                 Name                 | Score | usecMemTest | usecOpcodes | usecVidMem | usecMemEA | usec3DGames |  | Average |
+--------------------------------------+-------+-------------+-------------+------------+-----------+-------------+--+---------+
| IBM PCjr (memory expansion)          |     4 | 3579        | 1660        | 2578       | 1811      | 1773        |  |         |
| IBM PCjr (memory expansion, NEC V20) |     6 | 2415        | 1463        | 1877       | 1777      | 1348        |  |         |
|                                      |       |             |             |            |           |             |  |         |
| Speed difference (% faster)          |       | 48%         | 13%         | 37%        | 2%        | 32%         |  | 26%     |
+--------------------------------------+-------+-------------+-------------+------------+-----------+-------------+--+---------+


An explanation of the metric code:

usecMemTest: Performs memory read/write speed tests
usecOpcodes: Exercises every opcode once (except for HLT and the LOCK prefix)
usecVidMem: Performs video memory read/write speed tests
usecMemEA: Exercises all forms of effective-address calculations
usec3DGames: An instruction mix that mimics the inner loop calculation of a 3-D game (ie. does the 3-d rotation/translation matrix math)

As for the Score, that's a synthetic number you can use to compare systems with each other. "4" puts the PCjr in the same class as a 4.77 MHz 8088, and "6" puts an NEC V20 PCjr in the same class as a 7.16 MHz 8088.

I'm very surprised by the memory-heavy tests showing such an improvement on the PCjr, and don't immediately have an explanation for that. But everything else matches up with both the marketing claims of the chip and memories of using it: The speedup for all instructions (usecOpcodes) is 13% faster, and the average speedup across all use cases in the benchmark (which were designed to mimic situations where speed differences are more easily observed) is 26% faster.


Ooh, I never thought to run TOPBENCH on my PCjr... I should try that this afternoon (if I remember). I actually have a V20 *and* a SpeedUp mod on my system.
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Re: V20 vs 8088 Speed Test?

Postby Trixter » Wed Jul 05, 2017 8:33 am

Paste the result here if you do this and I can add it to the database.
You're all insane and trying to steal my magic bag!
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Re: V20 vs 8088 Speed Test?

Postby jmetal88 » Wed Jul 05, 2017 4:51 pm

Trixter wrote:Paste the result here if you do this and I can add it to the database.


Well, looks like it's in the database already! Scored a '9' which matches a submission by hexsane for a PCjr with the exact same configuration as mine.
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