The_Transactor_Vol07_04_1987_Jan_EpyxFastloadSwitch.pdf

this sequential file into a BASIC-format (SYMASS compatible)

program using Chris Zamara's STP program from Volume 5, Issue

06; or the C--64 BASIC STP found in the bits and pieces column in

the same issue as the unassembles Use STP to convert the file to

BASIC, then save the resulting source. This file is entirely compati

ble with SYMASS 3.13, and can be assembled immediately after

loading. Once you have changed the unassembler to its new

format, the conversions take no time at all.

1000 open 1,8,2, "file"

1010 sys 49152,#1,255,a$

1020 print a$;

1030 if st=O then 1010

1040 close 1

To read 128 bytesoftrack 18, sector0 (you can't read all 256 bytes

of a sector, since a string can only hold 255 bytes):

1000 open 15,8,15

1010 open 2,8,2, "#"

1020print#15,"u1:";2;0;18;0

1030 sys 49152, #2, 128, a$

1040 printa$

1050 close 15

Using the DOS Wedge

With Two Drives

Joel Pickett

Levelland, Texas

I use the DOS support program that comes with the 1541 disk

drive. I havetwodrives, butthe DOS program onlyworkson one. I

modified the DOS loader so it will run on the drive it is loaded

from. To do this, line 5 (below) was added — it peeks location 186,

which holds the number of the last device used. Also, the 'dv' in

line 10 replaces the '8'.

The program is fully relocatable; just change the assignment in

line 30 of the BASIC loader below. Using Fast File instead of GETs

will give you typical speed increases of nine to eleven times!

5 dv= peek(186): rem location 186 is current device #

10 ifa=0 then a=1: load"dos 5.1" ,dv,1

20 if a= 1 then sys 12*4096+ 12*256

30 new

10 rem** fast file **

20 rem read from afile into a variable

30 a= 49152: rem program is relocatable

40 print" usage: sys" ;a;" ,#<file#>,<# bytes>,

<string var$>"

50 for i=atoa+85: read d: c=c+d: poke i,d: next i

60 if c<>11661 then print" Idata error!": stop

70:

100 data 32, 253, 174, 169, 35, 32, 255, 174

110 data 32,158,183,134,251, 32,253,174

120 data 32,158,183,134,252, 32,253,174

130data 32,139,176,133, 73,132, 74, 36

140 data 13, 48, 3, 76,153,173,165,252

150 data 32,125,180,166,251, 32,198,255

160 data 176, 15,165,252,240, 26,160, 0

170 data 165,144, 208, 8, 32, 19,238,144

180 data 8, 76,249,224,132, 97, 76, 80

190data192,145, 53,200, 196,252, 144,232

200 data 32, 204, 255, 76, 100, 170

The DOS support program (at $CC00) gets the current device

number from location 186 and stores it internally at $CC77

(52343). Whenever you want to use a DOS command on another

drive, simply POKE 52343,(device number).

Shouldyou disable the DOSwith awarm start (sys 64738), you can

often run it again this way:

poke 186,8: sys 52224: return

Fast File

Rick Nash, MUlersburg, Ohio

Here is a short utility that can speed up programs that read from

disk files. It works with any kind of file, but it especially handy for

direct access (reading a given sector), since the INPUT command is

not always reliable under these circumstances. The INPUT com

mand stops reading data whenever it sees a delimeter character

(carriage return, colon or comma), so to read unpredictable data

the GET command must be used to read the bytes one at a time.

This is far too slow for most applications. The program below, Fast

File, will read a given number ofbytes from a disk file into a string

variable, and only stop reading when the given number of charac

ters have been read, orend of file occurs. It reads the data as fast as

the disk drive can supply it, since the program is in machine

language.

ModifyingThe Epyx

Fast Load Cartridge

James Craig

Waco, TX

When using the Epyx Fast-load cartridge with the C—128, you

have to shut off the machine and install the cartridge in order to

switch from C—128 to 64 mode. Besides being a nuisance, this can

quickly wear out the cartridge port.

I decided something had to be done. I took the Fast Load cartridge

apart and found that my troubles were little ones. I installed a

switch in the "EXROM" line to take the ground off the circuit when

using C-128 mode. By throwing the switch to connect the ground

and hitting the reset button, I was immediately in C-64 mode with

the Fast Load cartridge enabled! To go back to C-128, just throw

the switch to disconnect the ground, then hit reset again.

The syntax for using Fast File is:

sys49152,#f,n,v$

where 'f is the file number (the * must be present), 'n' is the

number of characters to read, and 'v$' is the name of a string

variable that will receive the data.

To open the cartridge, feel around the top surface for the indenta

tion ofthescrewthat holdstheunittogether. Just cutawayenough

to remove the screw. Cut around the box at the seam, then using a

For example, to read a sequential file:

Jan.1987: Volume7, toueO4

Tho Tronsoctof

knife blade, pry up all around the box and lift straight up to avoid Easy Retrieval

damaging the interlocking catches.

Dave Newberry

Duluth, Minnesota

of Last Filename Used

Install a SPST slide or toggle switch at any convenient location.

This could even be outside the case someplace. Cut the printed

circuit lead from the #9 male prong about where it makes a bend

goingto the EXROM connector. Soldera wire on each side and run

to each terminal of the switch — it doesn't make any difference

which wire goes where on the switch. Reassemble the case and

you're in business. Enjoy your C-64 again!

In the Bits & Pieces section of Volume 6, Issue 06, Jeffrey Coons

wrote in with a one-liner that allowed you to find the name of the

last file used (Finding the missing file page 5). Though the line

works well, there is an easier way to achieve the same result. A

singleSYS call is all it takes toget the name ofthe last file accessed.

The magic numberis62913. ASYS62913 will print the filename

on the screen for al! to see.

FAST LOAD

Chromatic Scale

Arne Storjohann

Scotland, Ont.

Thefollowing routine generatesthe SID chip registervalueswhich

correspond to eight octaves of chromatic scale. The values are

separated into high and low byte format and stuffed into two

ninety-six element integer arrays to allow for maximum speed of

use later in your BASIC program. Due to the ninth place constant

D, thevalues generated are exceedingly precise, limited in resolu

tion only by the 1 through 65535 range imposed by the SID chip.

The usual approach is to use data statements and read the 192

values into an array, but with a running time of less than three

seconds, this routine is much more compact, efficient, and above

all, a more elegant solution.

Anyone who has ever tried to program music on the 64 will

appreciate this algorithm!

rem** routine to generate chromatic

rem** scale register values (hi/lo)

rem** by arne storjohann - 86,05,04

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1541 Disk Swap Checker

John Chong, Syracuse, NY

dim lo°/o(95),hi%(95): g=2t(1/12)

f=3520*g*g: d =0.06095948: b=256

for i = 95 to 0 step -1: n =f/d: hi°/o(i) = n/b

lo%(i)= n-hi°/o(i)*b: f=f/g: next

The following program waits until the current disk in the drive is

removed, and another disk (or the same one) re-inserted. It does

this bychecking the write-protect status of the drive to see if adisk

is there or not. It only works if the disks being inserted are NOT

write-protected, and even then it can be fooled if you partially

remove and then re-insert thedisk. Although not bullet-proof, the

program shows the technique ofchecking the write-protect status,

and the subroutine at 3000 that actually does the checking may

come in handy in one ofyour programs.

rem ** demo **

s= 54272: for i = s to s+15: poke i,0: next

poke s+5,96: poke s+6,251: poke s+4,33

poke s+ 24,15: for i =-72 to 72

x = 71 -abs(i) +16: poke s,lo°/o(x)

poke s+ 1 ,hi°/o(x):for j = 1to200: next

next: pokes+4,32: end

2000 print" please change disks."

2010 open 15,8,15

2020 gosub 3000: if a<>0 then 2020

:rem waitfor diskto be removed

2030 gosub 3000: ifa<>16 then 2030

:rem wait for no disk in drive

2040 gosub 3000: if a<>0 then 2040

:rem waitfor disk to be inserted

2050 for d = "I to 1500: next: close 15

2060 print"ok, thanks!"

2070 end

2080:

3000print#15,"m-r";chr$(0)chr$(28)chr$(1)

:get#15,a$:a= asc(a$)and16:return

C-64 Underlined Characters

D. Munro

Port Elizabeth, South Africa

This program isbased on theC-64 italicsprogram in Bits& Pieces,

Volume 7 Issue 01. Instead of giving italics in place of reverse

characters however, it gives underlined characters. Both of the

64's built-in character sets are altered, so that underlined letters

are available from either upper/lowercase or graphics modes. The

new character set is located from 8192 (hex $2000) to 12287

($2FFF). Consequently, the start of BASIC is moved to $3001.

Tho ironsocior

Jaa1987: Volume7, toueO4

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