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update readme. 5X: move 'Apple IIc +' left a few spots

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mgcaret 2017-03-11 11:02:13 -08:00
parent aa0ee5829a
commit 08b1892f0a
2 changed files with 14 additions and 7 deletions
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8
rom5x/B0_FB68_center_title.s Normal file
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@ -0,0 +1,8 @@
; center "Apple IIc +" on the screen
; for some reason Apple added " +" on the title, but
; then displayed it two characters to the *right* rather than one
; or to to the left. It's a major
; pet peeve of mine, more so than the beep.
.text
sta $040d,y

13
rom5x/README.md
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@ -1,15 +1,14 @@
# ROM 5X by MG
## PRELIMINARY, DO NOT EVEN TRY THIS YET :-)
## PRELIMINARY, NOT EXTENSIVELY TESTED
**Warning:** This has not been tested on an emulator or a real Apple IIc Plus.
This is ROM4X revised to the Apple IIc Plus ROM version 5.
This is ROM 5X, providing the ROM 4X functionality to the Apple IIc Plus ROM
version 5.
There are almost no free bytes in the main bank of the IIc Plus firmware, so
I had to get creative to get into the alternate bank, where I then had to split
the code up across multiple smaller free spaces. Ironically this makes the
code larger as well.
the code up across multiple smaller free spaces due to the massive 3.5 drive
handling code. Ironically this makes the code larger as well.
For those interested, I hijack the monitor BEEP1 routine. The beep routine has
an LDA #$40 and then calls WAIT with this value for a .1 second delay,
@ -18,7 +17,7 @@ presumably so that multiple beeps are distinct from each other.
I patch the JSR WAIT to be STA $C028, which switches to the other bank.
The code in the other bank checks the accumulator and for two values calls
either reset5x or boot5x, and for any other value executes the WAIT (assuming
that we got there from BEEP1).
that we got there from BEEP1) and returns back to BEEP1.
Then, in only 6 bytes I can create two entry points that load the value into
A that we need for the reset or boot routines, and then jump to the above patch.