Volume Number: 15

Issue Number: 9

Column Tag: Tips & Tidbits

Tips and Tidbits

by Jeff Clites <tips@mactech.com>

Easy-to-Read MacsBug

If you spend very much time in MacsBug on a color screen, you know what the color

dot/bar pitch does to small fonts, and you might really yearn for a better font in which

you can easily distinguish fuzzy hex digits by their overall shapes. Whoever did the

font in MacsBug obviously did not do any time-and-motion studies on character

recognition. The worst offender is the gratuitously slashed zero, which is very hard to

tell from both the eight and the (cap) letter "B". There are a (very) few times when

you need to distinguish a zero from the letter Oh, but most of the time it's in a strictly

hexadecimal setting.

I have been using a modified Monaco font for many years now, in which the hex digits

are carefully crafted to be easily distinguished. It saves eyestrain and substantially

increases productivity. However, until recently I had to muddle along with the

illegible blur that MacsBug puts up. Here is how to fix your copy too.

Only three characters need work, zero, and the letters "B" and "D". I also improved the

letter "A", but the benefit is less marked. These are the pixels you need to be concerned

with:

Old, illegible:

x x x x x x x x x x x x x x

x x x x x x x x

x x x x x x x x x

x x x x x x x x x x x x x x

x x x x x x x x x

x x x x x x x x

x x x x x x x x x x x x x

New, improved:

x x x x x x x x x

x x x x x x x

x x x x x x x x

x x x x x x x x x

x x x x x x x x x x x

x x x x x x x x

x x x x x x x x x x

By narrowing top and bottom of the zero, we make it easily distinguished from the

more rounded letter "O"; removing the slash makes it visibly different from eight and

"B". The letter "B" is further distinguished from eight by extending the serifs out to

the left; the same change on "D" distinguishes it clearly from both zero and the letter

"O". The more pointy top of the "A" helps distinguish it from eight. The letter "C" opens

to the right, while "D" appears to open to the left.

How To Do It

Start with a copy of MacsBug. You will need a hex file editor that works on the data

fork.

MacsBug has its own font, which has grown over the years, but the bits in memory are

still relatively recognizable. Each character is the leftmost five bits of a byte, with

ten pixel rows, seven for the main character cell, two descender rows, and one

ascender for parentheses and a few others which rise above the regular character

height. Since this is not drawn with QuickDraw, there is no need for RowBytes to be

even-and in some versions of MacsBug it's not. The pixels are pretty easy to find in a

hex file editor: just search for "8888 8888". In different versions of MacsBug, the

font gets linked into different parts of the file, so you just have to look for it.

After you find the pixels, you need to determine the RowBytes. The top row is mostly

zeros, but the font begins with space, "!", quote, and "#" (in ASCII order), so the

beginning of the second row is pretty recognizable as "0020 5050". Now look for the

third row to begin with "0020 50F8" anywhere from 99 to 186 bytes later (more or

less). The exact distance is RowBytes, but you should check it on the characters you

are changing.

Sixteen bytes after the space, the digits start with zero, and 17 bytes after that the

letters start with "A". You will look for patterns like these and make the noted changes

(don't forget, words may align differently if RowBytes is odd):

0 1 2 3 4 5 6 7 8 9 A B C D E

7020 7070 10F8 70F8 7070 0000 0000 0070 7070 F070 F0F8

20 20 E0

8860 8888 3080 8008 8888 0000 1000 4088 8888 8888 8880

50 20 48 50

9820 0808 50F0 F008 8888 2020 20F8 2008 E888 8880 8880

88 50 48 48

A820 1030 9008 8810 7088 0000 4000 1010 A8F8 F080 88F0

88 50 70 48

C820 2008 F808 8820 8878 2000 20F8 2020 F088 8880 8880

88 F8 48 48

8820 4088 1088 8820 8808 0000 1000 4000 8088 8888 8880

50 48 50

7020 F870 1070 7020 7070 0020 0000 0020 7088 F070 F0F8

20 E0

Save the changes, and after removing the original MacsBug to a safe place, drop your

new improved version into the System Folder and reboot! If you made a serious

mistake, you can hold the shift key down and reboot again to remove it. Small mistakes

will just look funny on screen. But if all goes well, you should immediately notice

improved productivity while reading MacsBug screen displays. It also looks brighter!

Tom Pittman

<72457.2237@compuserve.com>