Editing JiffyDOS Kernal Upgrade (section)

== Performance ==

CMD's own published figures. '''The times are rounded to the nearest second and exclude drive spin-up (about half a second) and directory-search time''', which is why a stopwatch on your own machine will not match them exactly.<ref name="man" />

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Table 1 — C-64, SX-64 and C-128 in 64 mode, seconds'''<ref name="man" />
! Operation !! 1541 stock !! 1541 Jiffy !! 1571 stock !! 1571 Jiffy !! 1581 stock !! 1581 Jiffy
|-
| Load 202-block PRG || 124 || '''12''' || 124 || 9 || 102 || 8
|-
| Save 100-block PRG || 75 || 24 || 75 || 20 || 40 || 15
|-
| Read 125-block SEQ or USR || 84 || 15 || 84 || 13 || 63 || 9
|-
| Write 100-block SEQ or USR || 81 || 27 || 81 || 24 || 44 || 17
|-
| Read 64 × 154-byte REL records || 40 || 14 || 40 || 14 || 37 || 10
|-
| Write one 154-byte REL record || 0.350 || 0.125 || 0.350 || 0.120 || 0.325 || 0.110
|-
| Read/write 16K on the command channel || 47 || 9 || 47 || 9 || 47 || 9
|}

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Table 2 — C-128 in 128 mode, seconds'''<ref name="man" />
! Operation !! 1541 stock !! 1541 Jiffy !! 1571 stock !! 1571 Jiffy !! 1581 stock !! 1581 Jiffy
|-
| Load 202-block PRG || 124 || '''12''' || 14 || 9 || 12 || 8
|-
| Save 100-block PRG || 75 || 24 || 48 || 25 || 26 || 14
|-
| Read 125-block SEQ or USR || 84 || 15 || 31 || 12 || 20 || 10
|-
| Write 100-block SEQ or USR || 81 || 27 || 48 || 33 || 20 || 11
|-
| Read 64 × 154-byte REL records || 40 || 14 || 21 || 14 || 17 || 10
|-
| Autoboot 202-block program || 125 || 13 || 54 || 10 || 13 || 9
|-
| Read/write 16K on the command channel || 47 || 10 || 10 || 6 || 10 || 6
|}

Two things the tables make obvious, and which earlier versions of this page got backwards:

* '''The biggest wins are on loads and on command-channel traffic, not on saves.''' A 100-block save improves about threefold; a 202-block load improves roughly tenfold.
* '''The 1581 is not the weakest case.''' In 64 mode a 202-block load on a 1581 goes from 102 s to 8 s — a bigger proportional gain than the 1541's. The machines where JiffyDOS adds least are the ones that are already fast: a 1571 or 1581 under native C-128 mode, where the burst routines are already doing most of the work.